Hey, another untethered vulnerability found ! :-)
Look at the registers, all are controllable :-)
This is excellent news for jailbreakers many of which have been without an untethered jailbreak for quite some time.
Both comex and the Chronic Dev-Team have untethered jailbreaks in the works. The Chronic Dev-Team recently demonstrated theirs and plans to release it soon.
If you have your iOS 4.2b3 SHSH blobs saved and need to untether you can follow this Mac tutorial. An upcoming update to redsn0w will bring support for iOS 4.1 SHSH blobs and Windows.