On November 4th, Geohot released Blacksn0w, a jail break + unlock + hacktivate combo for Apple iPhones running firmware 3.1.x and baseband version 05.11.07. Geohot’s previous Blackra1n release was only able to jail break firmware 3.1.x but could not hacktivate or enable GSM unblock for any-sim use. See the definitions guide below for clarification on these terms.
Stay tuned for updates!
NOV-03-09, 2040 hrs – Update: Check out this post from Geohot!
NOV-04-09, 0020 hrs – Blacksn0w is now live, download it here!
NOV-07-09, 1245 hrs – Update: Some commenters are reporting a lingering problem with WiFi while using blacksn0w.  Some are able to solve it with a single “Reset Network Settings†but others say they need to do that periodically.  So far there seems to be no pattern to those affected or the best way to fix it.
Definitons:
Jail Break = Allows the installation of non Apple App Store applications onto an iPhone via direct .IPA installs or application repositories from Cydia, Ice and Rock.
Hacktivate = Allows the activation of an AT&T iPhone without having an AT&T SIM card installed, allows the phone to be activated for use on a non-AT&T network.
Unlock = Removes base band restrictions so that any SIM card from any phone network can be used in the iPhone.
Baseband = The baseband is the software interface for the GSM modem in the iPhone. In order for an iPhone to be unlocked (for use on any network) and hacktivated (activated for use outside AT&T’s network), the baseband must be hacked.