I'm at 100% right now and the little "feeding" light on the side is out. So, its 100%. I'm leaving it plugged in, but I'm dubious at this point.
Will report back in a week. Maybe longer.
I DID notice my phone went frmo 70% to dead in the span of about 1.5 hours a few weeks ago, under heavy usage (shoutcast stream, texting and surfing the internet all at the same time for about 1.5 hours straight). Wasn't happy about that, so I'll just leave my phone plugged in all tonight and most of tomorrow and see what happens.