The Limera1n jailbreak is ready and willing for your 4.1 iOS device--and at this point, we really hope it's not the iPhone 3G that's running that thing.
But here's the kicker of the Limera1n jailbreak: it's for Windows only, and it's not expected to work with Apple TV (though the website says it's "technically supported") or come available for Linux and OS X users for quite some time.
In addition, the jailbreak that was supposed to be released yesterday, Greenpois0n (remember? that whole 10/10/10 thing?) has been put on hold while the team clicks and clacks away at the Limera1n jailbreak to actually bring it to the appropriate demographic.
The iPhone Dev Team plans on implementing this LimeRa1n jailbreak into a future release of the Pwnage tool. We recommend waiting for that upgrade if you're down with jailbreaking. Also, jailbreaking your device voids the warranty, so do keep that in mind when you do so.
Anyway, so if you have dual booting on your Mac, you'll probably be able to play around with this thing. But if you don't, then you're just going to have to wait awhile with the rest of us. Le sigh.