@BitFlipper: WPF like would be a better way to describe the UI side of things.
Until the hardware people start making boards on this, you could always have a play with the .NET MF, after all Gadgeteer is basically a bunch of libraries on top of NetMF 4.1 as I understand it plus some hardware specs for interfacing the modules. So if you want to have a play have a look at some of the boards out there already like the ones from GHI http://www.tinyclr.com/compare/
If I can find some time I think a nice idea is to build an arduino like shield for the existing netmf boards that map their IO to the socket types for Gadgeteer so you can use the Gadgeteer modules if you want (when people start making them).
@Clint:If you get chance to talk to him, it would be intrasting to see what the uptake from the hardware vendors has been like, I know this is kind of standing on the toes of systems like (Net/Ar)duino and the system GHI already has, but I think as a total solution this has been thought out better. Also be intreasted to know about the value add tooling like the visual designers they've mentioned before, have they made any progress with those they can share. One final thing, their douments mention using VSIX to to package the modules, was wondering if they've thought to use nuget, seems to fit the use case better than VSIX?