Here's what I think is the most important question right now for the .Net developer considering new applications. It may be invalid, but here goes:
Silverlight, or MVC?
To me, silverlight turns the browser into a desktop application; when I worked on silverlight, I no longer thought about GET/POST whatsoever. Yes, I still get data from services, but I'm almost completely unaware of HTTP. Moreover, it seemed to lend itself to very clean applications from a pure OO perspective; same exact OO style on client and server.
With MVC, I'm thinking GET/POST over HTTP all the while. I'm getting back to basics in that regard (stepping back to the way things were before MS took desktop development and jammed it into the Internet with WebForms).
IMO, blending silverlight with MVC is a bastardization (don't take it personally if you're doing it). URLs need only have meaning in silverlight applications as a shortcut to start your application. In any case, I consider WebForms legacy for non-trivial applications. Still very useful when needed, but legacy.
So this is my question for today's .Net developer: "should we think about our new application like we did with desktop apps, or should we consider it RESTful?" Obviously, there are myriad other considerations; I just think this may be the most pertinent.