You probably don’t even care about any of this. If that’s true, ignore it. Testing results for http://www.jailbreakme.com/:
3G/4.0 – Untested, jailbroken with Pwnage Tool
3G/4.0.1 (UPDATED from above) – Failure, Safari crash to SpringBoard. Reboot spawns reboot loop.
Entered DFU mode to restore to fresh stock 4.0.1.
3G/4.0.1 (stock restored) – Great success! High five!
3GS/4.0.1 (fresh restore) – Great success! High five!
Haven’t tried yet, waiting for MMS/FaceTime fix (since I actually use this phone) Great success! High five! And MMS/FaceTime both work now too.
3G/3gS also unlocked with Ultrasn0w, 4 not yet (and I have no sim to test with anyway).