Plenty has been said about this around the web, but it's pretty exciting that the first p&p Software Factory with a substantive DSL Tools component is now live.
You can find
The MSDN homepage at http://msdn2.microsoft.com/en-us/library/bb931187.aspx
The main CodePlex site at http://www.codeplex.com/servicefactory
Apart from being a fantastic example of a rich factory, it has plenty of very interesting goodies from a purely DSL perspective too.
Firstly it has the beginnings of our thoughts on orchestrating code generation (T4 and other) in a more sophisticated way across large-scale solutions. Check out the code generation framework and tell us what you think. We're keen to get feedback on whether this is hitting the right pain points and capturing the right scenarios before we start to push similar features into the core VSX platform.
Secondly, it expands on the validation framework native to the DSL Tools with a hybrid approach using the validation app block from Enterprise Library.
Thirdly it has the notion of virtualizing the projects in a solution that work in a factory happens in using the concept of "roles". This lets you indirect tools that need to understand solution structure to match the way you've shaped your solution. Again we're keen to understand whether this is critical to you and meets your needs .
Please dig around - there's an awful lot in there.