Its still RC keep in mind, but according to the site, unlock is in place.  I have been holding off on upgrading from 3.0 till I was sure I could unlock.  Now I have no plans to unlock from AT&T, but I always want to be sure I CAN if I need to. So it looks like we are in business. From the site:
new visitors, go to blackra1n.com download and have fun

blackra1n RC3 is also live for both Windows and Mac!!! Clean firmware 3.1.2 and baseband 05.11.07 are recommended.

Updates:
Unlock!!!
Hacktivation
Keep legit activation if activated before running app
15 seconds faster, you’ll feel it
Tiger + PPC support

Go to blackra1n.com to download
For support, blackra1n.support at gmail…but read this first

I will most likely upgrade and hack my phone this weekend.  I’ll post up my experience.