Yes, you did saw the truth. There are some Open Source projects from Microsoft’s staff. I’m not sure whether this is permitted by the official authority, however, there is, licensed under CPL (Not GPL), which is an Open Source Initiative approved Open Source License.

It’s now 4 days after the first import. Not sure whether Microsoft has officially approved this, but well, if it is, then this is a big step of the software giant. It is accepting Open Source internally by allowing its staffs to release their own work under an Open Source license.

See here for more details.