Microsoft Research has released a Beta of an inference engine/framework:

Infer.NET is a .NET framework for machine learning.  It provides state-of-the-art message-passing algorithms and statistical routines for performing Bayesian inference. It has applications in a wide variety of domains including information retrieval, bioinformatics, epidemiology, vision, and many others.

Infer.NET is currently released as a beta.  We are looking for early adopters who will try out the library and give us feedback on how well it meets their needs. Please use the forum to provide feedback, to ask questions, and to share the ways in which you are using Infer.NET. Alternatively you can send e-mail to [email protected].

Can't wait to give it a spin!