I have just had a very cool look at what is possible with a desktop application. Alan Lewis provided attendees at the eBay Developer Conference (ebaydevcon07) with early access to the San Dimas beta. San Dimas is built using Adobe AIR (formerly known as Apollo). AIR appears to be breathing new life into the old and stogy paradigm of the desktop application.
As a result, I've been able to use San Dimas hands on. Thus far, I'm pretty impressed. The speed of the application is good and it is very quite responsive (although I haven't tried without using high speed). Although, I'd argue that for any rich internet application a high quality internet connection is required. In addition, the user experience is much more robust and intuitiive than just using the eBay website.
Great job Alan! You and your team are to be commended. I can't wait to play with it some more and to see how San Dimas evolves.