Alan Lewis just sent me a note that they've released a new version of the eBay desktop in anticipation of a final release as soon as AIR/Flex go live. The new version adds international support so that you can select any eBay site you want (eBay UK, eBay Germany, ect). They've had "10s of thousands" of downloads of the application in beta form so it seems to be a hit with eBay's users.
I've heard various people ask what the point of eBay on the desktop is and that "who wants to use eBay offline" but that's not what the eBay application is about and I still think it stands as a very good use case for AIR. As Alan Lewis has often said, the application is really aimed at providing a better user experience around eBay. The application is a great way to manage auctions and is especially useful for the kind of user who spends a lot of time on the eBay website. AIR is a great technology for companies that want to extract some functionality and provide a more immersive, tailored experience to users than a browser can provide. That's what the eBay desktop is all about, not so much about being able to do things offline.