Well, SAML is a data format for exchanging authentication and authorization data and used mostly in federated identity scenarios. And it's not a new format and has support in .NET environment.
I don't think you need to use java based implementation in .net, you at least can find something similar for .net or just use combination of WIF, WCF and ADSF (or some of them).
You can find a bit more information here : Claims-based auth with WIF and here SAML based claims.
There is also very good free book from MS patterns & practices about Claims-Based Identity and Access Control here.