My only worry is these guys usually want to brag about how they managed to do their magic, giving Apple insight so they can quickly come up with a way to prevent it on the next software release. Thus I'm afraid Apple might patch the iOS before the Windows version even comes out.
But I'm as anxious as hell to try it out. I've been running on an unbroken ('D) 4S for a while now, and I'd really like to tweak it a bit.
They haven't mentioned how 'secure' the crack was, though. In terms of how long they think it'll last. I'd like to think this jailbreak will work thru all the releases of the A5 techology, but I'm not counting on it.