Upcoming jailbreak will probably work with iOS 4.1 also
The jailbreak hopefully being released within the next few days is, again, going to be a big one. "the upcoming new JB from @comex will be untethered and for all 4.x devices". Apple's signing window for 4.0 has already closed but you are able to get your SHSH blobs for 4.0.1.
So, for now, and as always, save your blobs and be careful of any updates though iTunes.