From the (Twitter) desk of Dev-Team honcho @MuscleNerd:
Or, in what FIREFLY's Mal Reynolds dubbed "Captain dummy speak:" if you have an iPod Touch 4G running the new iOS, you can now jailbreak it with limera1n. Since it's a tethered jailbreak, if you must reboot your iTouch, you will need to have it connected to your computer.
The links in the tweet are screencaps of (a) the iTouch sporting the Cydia and iSSH apps and (b) iSSH itself (above), displaying a bunch of kernel information at the root.
Significantly, this jailbreak occured less than twenty-four freakin' hours after iOS 5 was announced at WWDC. Indeed, the new firmware isn't scheduled to arrive in end-users' hands until the fall; what debuted yesterday was the developers' version. (Talk about your rapid turnaround…) And the dismissive tone of MuscleNerd's message suggests that the House of Jobs put little to no effort in plugging new or pre-existing exploitable holes in the iOS upgrade.