With this handy app you won't have to wait for the iPad 2 to start taking advantage of FaceTime. Currently the app is only on the Mac and you can only hope for a Windows version in the works.
Here's how you get started
1. Get the App from HERE
2. Download iOS 4.2.1 for the iPod Touch 4G from HERE.
3. Download PhoneDisk
4. Jailbreak your iPad on 4.2.1 (tethered or untethered, but of course untethered is preferred)
5. Start Cydia from the iPad and install OpenSSH and AFC2 (AFC2 comes with Greenpois0n by defeault)
6. Run PhoneDisk, enable Root and connect to it.
7. Run iFacePad.app and reboot.
and your finished
Here is a video tutorial too