I know stackoverflow uses OpenID authentication. I want to try and use this as well. I am using asp.net mvc 2.0 with C#.
I found this
http://www.dotnetopenauth.net/
and I am wondering if this is what was used for stackoverflow.
Also any tutorials would be nice as well.
Edit
I am trying to load up some sample projects but when I build it in VS2010 I get
Error 6 'System.Diagnostics.Contracts.ContractInvariantMethodAttribute' is inaccessible due to its protection level C:\Users\chobo2\Downloads\DotNetOpenAuth-3.4.6.10357\DotNetOpenAuth-3.4.6.10357\Samples\OpenIdOfflineProvider\TextBoxTextWriter.cs 73 4 OpenIdOfflineProvider
Error 7 The type or namespace name 'ContractInvariantMethod' could not be found (are you missing a using directive or an assembly reference?) C:\Users\chobo2\Downloads\DotNetOpenAuth-3.4.6.10357\DotNetOpenAuth-3.4.6.10357\Samples\OpenIdOfflineProvider\TextBoxTextWriter.cs 73 4 OpenIdOfflineProvider