If you remember the popular (sic) phrase
"All your bases are belong to us!". Here's a nice summary about Microsoft's
stance about open source:
"All your open-source codes are belong to us. And all the source codes that we share for open-source are still belong to us. And if you read our shared open source codes, you are belong to us!"
Overall, this is unfair. While Microsoft will freely use and make proprietary for profit, any contributions to the open source, they will not allow you to freely (without royalties and licensing) do a for-profit or commercial deployment using their shared open source. THIS IS VERY UNFAIR and ONE-SIDED OPEN-SOURCE scheme ever concocted!!!
Let it be both or all ways. ANYBODY CAN FREELY USE IN ANY MANNER FOR PROFIT or other purposes to create proprietary derivatives or finished products from all the contributed open-sourced codes! Anybody can freely contribute likewise, for the world to see. Just like a scientific and academic contributions where the only reward is the recoginition of an author's contributions.