You may have noticed Voice Memos recorder, which has been added in OS 3.0, under both OS versions 3.0 and 3.0.1 allowed for unlimited audio recording. And it was just great at that: it was indeed unlimited and the battery life impact of its operation was negligible. (Just for the record: I've run a test lasting for 1 hours and 30 minutes [the phone suspended almost all the time; the resulting file size is 52 Mbytes]; the battery level (on my 3G S) decreased from 98% to 90% during this. I've repeated the test on the 3G. In 1:10, the battery level decreased from 100% to 96%. That is, the battery life is excellent on both the 3G and the 3G S.) Not so in the latest, 3.1 OS. In it, Voice Memos won’t record for longer than 30…34 minutes, as is also pointed out in THIS Apple.com thread. Currently, no fix for the problem exists, which is pretty annoying as Voice Memos is, power consumption-wise, way better than third-party apps: while it records into high-quality but compressed m4a files, it doesn’t consume almost any power. I’ve tested, power consumption-wise, the most important alternative, VR+ by SHAPE Services 1.6, which, now, is on sale ($2 as opposed to the regular $3). I have finished testing: starting from 100% and a reset iPhone, running in the background most of the time in airplane mode with minimized backlight and default settings (read: no VAS; 64 kbps recording); after 48 minutes: 3G S was at 90% 3G was at 84% That is, these figures are WAY worse than those of the built-in Voice Memos. Interestingly, while the latter doesn't cause excess battery usage on the 3G, a third-party MP3 encoder (as one would except – see my 3G vs. 3G S power consumption tests HERE) already does. Conclusions If not absolutely necessary, don’t update to 3.1. Not only because of Voice Memos, but also the fact that, on the 3G S, currently (as of the just-released PwnageTool 3.1.3, see THIS) it seems you won’t be able to jailbreak your phone if you’ve already upgraded to 3.1. And, of course, jailbreaking is a must for all serious users – Backgrounder, for one, can’t be beaten, and that’s only one of the highly useful Cydia applications like YourTube, QuickScroller and the like. If you absolutely need Voice Memos’ recording over 30…34 minutes, stick with 3.0.1. Again, should you want to use alternatives recording into compressed (and not just the memory-wasting uncompressed AIFF done by most? all? other voice recorders) formats, keep in mind that they have a much higher power consumption than that of Voice Memos. And, of course, they can’t run in the background (while you use your phone for something else; e.g., Web browsing) unless you jailbreak your phone and operate it in the background. Which, of course, also means you can never be sure whether they still running (a major problem on the 3G as, because of the limited RAM memory, the operating system likes to kill background processes) – unfortunately, none of them has the same visual feedback (colored upper bar, visible from all other while recording) as Voice Memos.
Yeah, well some people had trouble just trying to update their iPhone to software 3.1. While the iPhone was in its restart loop, it froze and all of the apps hadn't been synced onto the iPhone yet. People had to downgrade their iPhone back to software 3.0, and for some people, their iPhone became completely unusable.