What's tweaked and changed? Well, editing the carrier file in iTunes to enable tethering is now apparently blocked, and MMS support on AT&T is also 'hidden' per the iPhone Blog. It's not 100% clear whether these feature drops are deliberate, as some reports say a clean install preserves the capabilities. Parental control features for apps now seem to be visible... and yes, the new beta has already been jailbroken.
Got more observations and tidbits? Let us know below.
Thanks to everyone who sent this in.