Confirming (per the iClarified claim...) mine, unlocked via Pwnage Tool, not jailbreaked, updated with the official 3.0 release via iTunes in Windows (just clicked okay when it asked me if I wanted to update) works (automatically activated and appears functional), modulo the following issues, of which I am aware:
- Like others above, Youtube does not work. It seems this happened in some circumstances with 2.0 as well (not to me, though). Perhaps it will mean either a different activation process in Pwnage Tool or else it might mean some kind of fix via a jailbreak tool....
- I'm not sure this is related to it being unlocked, but I had four homemade .m4r ringtones before the update. After the update, none of them work -- they show up in the list but don't make sound. I verified the files on the PC were fine, and manually unchecked them, synced, then re-checked them to force new copies onto the iPhone, and they still didn't work. (A sample of iPod songs seems fine -- no issues there). I made some new ringtones using the same .m4r process, as far as I could tell, not doing anything different (although the old ones may have been made with Sound Studio on a Mac; these were made with Audacity on Windows), and they work fine. Then made small adjustments to the existing ringtones, saved them as new .m4r files, deleted the old copies in iTunes, put the new copies in iTunes, and synced them, and these also work fine.

So I have working ringtones again, but what on earth was wrong with the old ones?
Otherwise I'm a-okay...
EDIT: I just realized my APN settings got blanked during the update before. Odd, that hasn't happened with a previous update. Once I restored the APN, though, EDGE data worked fine.
EDIT: One more thing I had not initially noticed was wrong: a couple more of my settings mysteriously changed, with everything else being set to normal. I wasn't getting any new mail, and then I realized that my phone had been set to Fetch->Manual, whereas it had been at Fetch->15 minutes. So far, I think this and the APN settings are the only ones that changed.