
The Chronic Dev-Team has announced via twitter an untethered jailbreak for iOS 4.2.1. This should work for iPhone 3GS (new bootrom), and iPad. And it will not require saved iOS 4.2b3 SHSH keys.
The untether is demoed in the video below. It’s a result of a collaboration between @0naj, @p0sixninja, and @pod2g. P0sixninja has previously said it will not require iOS 4.2b3 SHSH blobs.
A small bug with wifi still remains. They will release utility as soon as they fix it.
Here is a video proof: