http://www.telesym.com/products.html
These guys were apparently at Demo 2002 and made a hop over to VON and just walked up to Jeff and the other VON folks with their product. It was the first truly cool thing I have seen in years.
Combine an iPaq with an 802.11b wireless card, add this software and a headphone/microphone, and you are rockin’!
-Ian.