In the past two months I have seen 2 different sources that have a copy of Propeller Arena for the DC. Below is a link (to an excellent Dreamcast Page) where former owner of VGD (Tom Keller) acquired to GD Rom for Propeller Arena.
http://www.dreamcasthistory.com/index1.html
There was also an ebay seller that had the game for sale as well. I do not believe it sold.
For those who don't remember Propeller Arena was canned at the last minute (after the Sept 11th Terrorist Attacks), Sega felt that being able to control a plane , flying in NY was not apropriate subject matter.
Personally, I am dying to get my hands on this game. Any word on copies leaking out to the public, like Half Life?
Dustin