Amid the din of claims and counter-claims about the second-generation iPad, one prediction is pretty much a sure thing: it will do FaceTime. One clever modder has come up with a kludge to allow that on current iPads, though without a front-facing camera it'll only let you see, not be seen. It's an interesting bit of work, though it requires Apple frameworks and so couldn't be made into a Cydia app without violating copyright, which would be a dumb thing to do.
Someone going by the name of Intell posted a how-to over at the MacRumors forums on the process, which involves extracting some frameworks and the MobilePhone app from the iPod touch version of iOS 4.2.1 (there have been problems reported with the iPhone 4 version) and logging in via SSH to make some modifications. What you end up with is a MobilePhone.app that appears as FaceTime.app and lets you see FaceTime calls from other iDevices.
It's still at the kludge stage, and though Intell says he's working on an AppleScript to make the mods easier, it seems like people are having problems with their iPads despite doing all the steps right. And you still can't be seen, obviously, due to the lack on a video camera. However, if one day PhotoFast finally releases that iPad webcam they promised back in June, or somebody else figured out how to do it, this would be an awesome workaround... especially if you paired it with My3G.