Apple has already seeded the final Gold Master version of iOS 4.2 to developers. Public release is looming near. Once the new firmware is out, Apple will stop signing the old firmware, which will make it impossible for you to get SHSH blobs for iOS 4.1.
iOS 4.2 was released earlier today. Just like iOS 4.1 and iOS 4.0.2, the new iOS 4.2 at the moment is not jailbreakable. It also contains new baseband for all iOS devices which currently makes it impossible to unlock using existing version of Ultrasn0w. So if you rely on a jailbreak and unlock, stay away from this new firmware until new jailbreak and unlock tools are available for download.