PostSharp 2.1 SP 1 is released
PostSharp 2.1 SP 1 is now released. This is pretty much a maintenance release, addressing bugs.
There are some new features, including integration with decompiler tools (dotPeek, ILSpy, and Reflector are supported).
What's intriguing is the new features for and allusions to the PostSharp Toolkit, which could be a very interesting release from SharpCrafters.
Anyway, PostSharp is perhaps the most popular and stable tool for AOP in .NET. I'm not saying it's the end-all-be-all, but if you are interested in AOP for .NET, PostSharp is where I think you should start. You can download 2.1 SP1 (aka 2.1.6.4) at SharpCrafters.com, or just do it the easy way and get it via NuGet.