"Question for developers: which is going to win? MSFT's WPF or Adobe's Apollo? Why?"
I would like to add a new entry to this list? How about Mozilla's XUL? Go here to see some example apps. I think this is a serious contender. If you think not, let me know why in the comments.
Oh, and Adobe released Apollo last night. The SDK seems to only be available for Windows and Mac. No Linux.