Nothing at all and Everything in general.

RestSharp and Windows Metro

I've got RestSharp (partially) working on Windows Metro. I've been able to make a simple Metro application and make a few rest calls. Though right now some encryption and signature related functionality isn't yet working. 

I can't seem to run the unit test in Visual Studio 11 and may try to resolve that later this week. But if you want to take a look at my changes thus far you can find them on github.com