Clemens has posted a number of interesting posts about the .NET Services March 2009 CTP and SDK.
Introduction and new features
Queues and Service Bus Routers Both are new for this release and look very promising for a number of (reliable) messaging scenarios between parties separated with various NAT and firewall devices.
Miscellaneous
To get a great overview of all these posts you can also watch the recording of his Mix09 session.
This is an ongoing series, so I’ll update this post when he posts a new article. (Or you can just subscribe on his site.)