Okay, it may be something in the settings I didn't quite figure out. But when you first load Froyo there is not a 'Silent' Mode. Only different volumes and a 'vibrate' mode.
If you go into Sound Settings you can change the settings for vibrate (Always Vibrate, Never Vibrate, Vibrate when in Silent Mode, Vibrate when Not in Silent Mode).
Before, it was possible to have different volumes, a separate mode where all the phone did was Vibrate, and another mode where there was no sound, period (except Media, I guess). What happened?
Maybe there's just a different way to configure it?