Sure. All you need is WIFI access.  Basically the non 3G iPad is an iPad on steroids. So if you could get your ipod touch to do a VoIP call, then you can do it on your iPad… And there are plenty of Apps to choose from.

iPad with the back removed... Ah ha!

Line2 has the most professional options. (My Review of Line2) I like that you have a dedicated number with mailbox, redirect, quite times, and can support calling in as well.  HOWEVER, the app has to be running for you to get an incoming call. I think that will be sorted once jailbreak is in place and we can run that app in the background.

There are plenty of other options; Skype, TruPhone; Fring, Google Voice (requires jailbreak)  I have a list posts on VoIP here, so you can read and choose the best app for you.

You may also want to invest in a good wire or bluetooth headset. Holding that big iPad to your head is optimal and it makes you look plain silly. 🙂

Share and Enjoy !