Yes, this is a new name heard by me. I am very much beginner for DLR. I know little about DLR and the same sharing with you.
DLR stands for Dynamic Language Runtime, it would be a layer top on the CLR.
For more detail, must look these links:-
http://geekswithblogs.net/ranganh/archive/2008/07/24/dlr-hosting.aspx
http://blogs.msdn.com/seshadripv/
http://www.codeplex.com/sdlsdk
http://blogs.msdn.com/hugunin/archive/2007/04/30/a-dynamic-language-runtime-dlr.aspx