Using Google OAuth 2.0 With Unity

So recently Google unveiled their Google Play Games API. I was quite surprised to see a REST API in the documentations. Hm, a browser and standalone Unity game that uses Google APIs for login, achievements, and friends lists? Sold!
The problem is using OAuth 2.0, required by Google to access any of the Games APIs.
The problem I run into is when importing DotNetOpenAuth.DLL, I end up with an internal compiler error.
Has anybody tried using Google’s OAuth 2.0 APIs from Unity3D? It would be nice if I could get this working.
Thanks.

What’s the error ? Probably it’s built for .net 4.0

I’m pretty sure it was a type import error