There appears to be an issue, verified by others, after the 2.0.1 update. I was one of the few to get the update over the air.
The issue is that, perhaps after unplugging headphones, you cannot hear audio from the earpiece. I have to enable speakerphone to hear, or use a headset. Rebooting fixes the issue. I posted this on AndroidForums and have gotten others to confirm:
http://androidforums.com/motorola-droid/25297-cannot-hear-earpiece-phone-after-2-0-1-update.html