The latest version of blackra1n from GeoHot promises to jailbreak the iPhone OS 3.1.2 with ease and comes with few fixed bugs reported from last version.
The Blackra1n RC2 fixes the following isssues:

Tethered jailbreak for 3.1 OOTB ipt 8GB and new 3GSes
Solved Icy issues
Fixed 3G issues

The Blackra1n RC2 comes for both PC as well as Mac users. The latest version is for those who were not able to jailbreak successfully using the last RC1 version.
If you are facing problems like …