blacksn0w, the free unlock for iPhone 3G/3GS with baseband 05.11.07 has just gone live. It can be downloaded form blackra1n. blackra1n RC3 has also gone live with the release and is now Tiger + PPC compatible for the Mac OS X version. Check out our helpful guides on unlocking and jailbreaking using blackra1n RC3:
blacksn0w is also available on Cydia now. Just add blackra1n.com as repo and install blacksn0w.
Happy unlocking and jailbreaking!