We wrote some code in this session.  Some notes:

It was really easy to suck up a .NET web service in Flex with a few MXML tags.  Flex Remoting, not so much.  However, Flex Remoting provides a bunch more stuff (security management, performance, etc).

In order to communicate from Flex to the .NET class using Flex Remoting, you need to have something in between.  In our session we used WebORB, which is supposed to be free for the standard version.  It was more complex to use than the web service side.