Microsoft starting to OpenSource it's code base?????

The Register has an article that talks about Microsofts recent Open Sourcing of some code.  They have apperantly opened the source for several Office Plugins and about 20,000 lines of Windows Kernel Code.  While Microsoft doesn't seem to be giving a timeline or even a list of things to be open sourced.  This seems to fly in the face of the MS leagal department who just recently fought and won a case against Tom Tom for their use of the FAT File System.  Tom Tom's are Linux based and have the ability to mount USB and SD cards.  To do that they choose to use the FAT file system that came with the older DOS Operating system that proceeded Windows.  This will be an interesting situation to keep an eye on.  What the final plan is coming out of Redmond seems to be set to come to light over the next couple of months.

What do you think Microsoft should open source first?