The autofocus still uses only three focus points, and yes, that makes a difference. I found it to be slower than autofocus on cameras that use more focus points. It tended to hunt sometimes, even in broad daylight. But overall, it worked pretty well, and the focusing delay wasn't significant.
Battery life is advertised at 650 shots per charge. In practice, I found that I got about 800 shots per charge. Maybe that's just me. I always seem to get more shots per charge than the specs.
I use Adobe Lightroom to post-process all my photos, regardless of what camera I use. I noticed that RAW files created by Olympus cameras (both the E-500 and E-510 are subject to this), take longer to load fully in Lightroom than RAW files created by Canon cameras. I'm not sure why this is, and whether it occurs with other workflow-oriented applications, like Aperture, but I thought it worth mentioning. Just in case you're wondering, I did upgrade to the latest version of Lightroom as of this date, which is version 1.2.
Sensitivity to low light was a point of contention in my review of the E-500, where I noted the CCD sensor was prone to lots of chroma noise at higher ISO. Presumably, the Live MOS sensor of the E-510 has better low light performance and generates less noise. In terms of ISO speeds, it goes from 100-1600, like the E-500. I did find less chroma noise when I used it. Luminance noise was about the same, perhaps a little more, but that has to do with CMOS sensors in general. Basically, I can't give you a definitive opinion on this. The two kit lenses that shipped with my review unit were too slow to properly judge how this camera does in low light situations. The 14-42mm lens was f/3.5-5.6 and the 40-150mm lens was f/4.5-5.6. To judge a camera's performance in low light, you'd need faster lenses, ones that can open up to at least f/2.0. Ideally, the lenses should open up to f/1.8, f/1.4 or f/1.2. I asked Olympus to send me such a faster lens, but they weren't able to do that within the review period. As I told them, I'd be glad to test the camera with a fast lens if they can arrange it at some point in the future, and report on my findings.