Magic Mouse battery management

If you have a wireless Mighty Mouse and you're tired of the scroll ball getting clogged with gunk, you may consider buying a new fancy Magic Mouse. In many aspects it will be a step forward, except one.
The battery management of the Mighty Mouse was very good: it could run on a single cell, which means that when it told you its batteries were empty they were both guaranteed to be empty. The mouse would always keep drawing power from whatever battery still had some juice left. This made it possible to run for weeks even on a set of old worn-out rechargeable cells.
The battery management of the new Magic Mouse is not so mighty, nor is it magical. In fact it is absent. The people at Softpedia have already discovered this but they did not explain the root cause of the problem. I do not believe the Magic mouse draws much more current than the Mighty Mouse. The problem is that it treats the two cells in series like any primitive battery-powered device. It expects a total voltage of more than about 2 Volts. This means that if one battery is still going strong at 1.2V and the other one is dead at 0.8V, the mouse will shut off. The Mighty Mouse would still be going at that point because it would ignore the empty battery and draw current from the other one.
Especially with Apple now selling their own NiMH batteries and charger, their decision to drop the advanced battery management is puzzling. If there is any type of battery that benefits enormously from the separate treatment it is rechargeable ones. Contrary to alkaline batteries, NiMH batteries will maintain a quite steady voltage until they're empty, at which point they exhibit a very quick voltage drop. If one battery has less capacity than the other, this leaves no margin for the higher-capacity battery to further discharge because the series voltage plummets below the threshold. With alkalines the steadily dropping voltage provides more spring-action between the two cells.
I tried using 2300mAh cells in a Magic Mouse and they lasted less than two weeks of non-intensive usage. The scenario was as described above: at the end of the run one cell was empty and the other one still had quite a lot of juice left.
If you have multiple pairs of rechargeable batteries and a means to measure their actual capacity (e.g. with an advanced charger), try to match the batteries in pairs of equal capacity. They will give you more mileage. This does not only apply to the Magic Mouse but to any device that connects its cells in series (i.e. practically every device).
P.S.: Anyone who had a wireless Mighty Mouse might remember reading the mysterious notice “3Vdc Agency approvals inside” on its underside. Whatever it meant (I never found any ‘approvals’ while disassembling the mouse), I think the 3Vdc Agency would not approve of the Magic Mouse.

Mac OS X Lion: one month later

It has been about a month since I upgraded to Mac OS X “Lion”. In short, here's what I like and dislike so far:

Like:

1. ‘Natural scrolling’: it took surprisingly little time to get used to and after this short adaptation stage it proved so much more intuitive, even for the scroll wheel. And I don't even have any iOS device. I even tweaked my Linux environments to reverse their scrolling.
2. Applications and their open windows are remembered between logins. Especially handy for Terminal, which will even show previous output in gray.
3. The weird LCD backlight issue where the screen would sometimes light up again after dimming is fixed.
4. The acceleration curve of the mouse has changed to more resemble the acceleration under other operating systems. I believe the previous acceleration curve had remained unchanged since the introduction of the Macintosh in 1983, but I have always been annoyed by its extreme acceleration behaviour at very low cursor speeds. When going from OS X to Windows/Linux I never noticed anything unusual about the mouse, but when coming back the weird acceleration always took a while to get reaccustomed to.

Dislike:

1. My mouse cursor will often make unexpected jumps. Many other people have this issue and Apple is aware of it, but it still isn't fixed. It seems to happen mostly with third-party mice like my Razer Imperator. If you also experience this and want to have it fixed sooner, file a bug report at http://bugreport.apple.com and refer to bug ID #9701670.
2. The Finder does not play well with the remembered windows feature. Sometimes I see my previous windows vanishing into thin air immediately after logging in.
3. Instead of the LCD backlight issue, now the keyboard backlight will sometimes be blazing at full intensity when I return to my MacBook Pro after a while, even though I had turned it off.
4. There is often an annoying delay in ‘open/save file’ dialogs, with the hard drive rattling for reasons unknown.
5. There is still no good free Lion-compatible VNC server that I'm aware of (I'm waiting for an update to Vine VNC) and the built-in screen sharing is awful. It only supports bandwidth-gobbling lossless compression, it incorrectly assumes the command key is pressed at certain moments and worst of all, logging in requires a dozen attempts on average — unless you know the following trick. The issue is that when connecting, the login screen will only start to react to input after about five seconds and only during a random time period that ranges between zero and ± seven seconds. However, anything you do in those initial first five seconds will be buffered and executed. Therefore, click your login name as soon as it appears and immediately type your password + enter, even though you don't see anything happening. Just wait for ten seconds. If you're not too unlucky the connection will not freeze before your cached clicks and keystrokes have been executed, and you will be logged in. This still does not work every time but it increases your chances of getting in to something like 50%. Have fun playing login roulette!
6. The lack of scroll arrows makes it hard to impossible to advance a single line (or other unit) while scrolling.
7. Joesoft's ‘Hear’ still is not Lion-compatible, therefore I have to do with the standard sound quality of my headphones, which is not stellar despite them being from Sennheiser.
8. The XiphQT plugin has not been upgraded to 64-bit. No biggie since iTunes can be set to run in 32-bit, but I don't like to have to do tweaks like that.

Despite the ‘Dislike’ list being much longer than the ‘Like’ list the overall experience is still positive, but if there is no immediate reason for you to upgrade to Lion I would recommend waiting until it is a bit more mature and software developers have caught up.

If you're using Fink and can live with sticking with current release versions for a while, you can do an upgrade to Lion and keep using most of your existing Fink installation. I have found only few things that stopped working. Eventually you will need to reinstall everything from scratch however. When you're going to do that, be prepared for a disappointment because many packages are still not compatible.