(Note there were no sessions devoted entirely to Microsoft's current desktop solution WPF)
To that point they reiterated their support for the Mac meaning Silverlight is an environment that can be used for out of browser apps that run on both Mac and PC (much like Adobe AIR).
Microsoft's position on HTML5 and Silverlight seem extremely clear to me. If you're doing cross-platform their focus is now HTML5. You won't see much of an investment on Silverlight for the Mac, for example. But if you're developing exclusively for Windows, then Silverlight is your best bet.
Regarding WPF at Mix -- Mix is a web conference and WPF is NOT a web technology. Expect WPF sessions at PDC (a couple to a few at most), although I do think that WPF and Silverlight are merging (with Silverlight basically just catching up to WPF, with WPF being left to handle niche Win32 interop scenarios).
Can you resolve this with the following excerpt of Tom's comment?
"To that point they reiterated their support for the Mac meaning Silverlight is an environment that can be used for out of browser apps that run on both Mac and PC (much like Adobe AIR)."