I had very simaler problems and suspected it had to do with iTunes 7.7.1 update - because before that update, my iPhone, apps - all worked fine.
My phone would crash during syncs, but a normal reboot would fix it... after about 1-2 weeks of this, my phone would not reboot at all and just hang on the "apple screen" forever. I did 5 backup restores on the phone, nothing worked.
Read some of the info here and on the Apple support forums... and this is what is working for me now:
Deleted:
/System/Library/Extensions/AppleMobileDevice.kext
/System/Library/PrivateFrameworks/DeviceLink.framework
/System/Library/PrivateFrameworks/MobileDevice.framework
/Library/Receipts/AppleMobileDeviceSupport.pkg
And then after, deleted iTunes 7.7.1 itself, reboot Mac...
Installed fresh copy of 7.7
Put the phone into "recovery mode" by holding down Home button while connecting to dock
Had iTunes restore phone to original settings, then chose to set up as a "new phone".
Warning: This will wipe out *everything* on your iPhone!
I lost some photos, but I use MobileMe, so all my contacts, calendars, etc. synced back up.
Been about 24 hours now, I've done 3 syncs and iPhone is running GREAT!
No more freezes, crashes - all apps working fine... I'll even go as far to say that 2.0.1 firmware feels.... "snappier".
As others have said, it really seems that iTunes 7.7.1 is the main problem here. Something definitely gets screwed up during syncing, not sure if it's the DRM or what... Go back to 7.7 and you might be fine.
note: I always install my apps through iTunes on Mac - NOT from App Store on iPhone.