In my post about the IronPython 2.0 Alpha release, I wondered how the mono team would implement or support DLR. The answer appeared in this post by Miguel de Icaza
"The release for the DLR is done under the terms of the Microsoft Permissive License (MsPL) which is by all means an open source license. This means that we can use and distribute the DLR as part of Mono without having to build it from scratch. A brilliant move by Microsoft."
Hopefully there will not be many changes required to the mono compiler and runtime so it will compile and run the DLR. Looking forward to running IronPython 2.0 on Mono soon.