In the search for a canonical explanation of ITness, here's my typical spiel:

It's a Nokia, but it's not a phone. It's what they call an "internet tablet," which means it can't make up it's mind whether it's a PDA or a laptop, but it's leaning towards laptop.
<As appropriate, expound on WiFi & BT DUN connectivity, note-taking ability, BT keyboard, VoIP, quetoo, or whatever other features seem likely to interest the newb undergoing proselytization.>
Then explain that it has replaced my laptop, because anywhere I have an internet connection, I can remote-control my desktop.