I've noticed my battery life has seriously started slipping as well. I've had my phone since May and also have 2 spare batteries. I'd noticed a steady decline during the summer but am now noticing drastic declines.
Part of it MIGHT be that I've switched buildings recently at work (and the reception isn't as great in this building), but I can't see it being that entirely. I take it off the overnight charger around 4:45am and go to work around 7:45am. By noon, I could easily be down to 50-60% with very little use (occasionally looking at it for news, or looking up something briefly on a website). I have checked the battery usages, but there's nothing glaring. Screen and Phone Idle are typically the top 2 spots.
If you notice anything, please update this thread, and I'll do the same.