Sherif Hashim, the man who discovered the exploit based on which the iOS 4.0 decryption solution was made announced today officially that a decoding solution for iOS 4.1 and iOS 4.2 is being worked on. The new decoding solution should be compatible with both baseband 05.14.02 and 02.10, i.e. the basebands to which you update if you install iOS 4.1 on iPhone 3G/3GS and iPhone 4. As Sherif Hasim says, for the time being the development of a decoding solution has begun, so everything is preliminary and will most likely last until after the release of iOS 4.2, that is, as confirmed and MuscleNerd this morning.
In case you didn't know, iOS 4.2 comes with a new baseband for both iPhone 3G/3Gs and iPhone 4, so probably the decoding solution will be compatible with those versions after it is released. This whole process could take at least a month, if not even 2, so either geohot will release a decoding solution a little earlier, or it is possible to have decoding/jailbreak around the Christmas holidays, but it all depends on the date Apple will release iOS 4.2.
