Microsoft has announced their Secure Content Downloader, which they're touting as "a peer-assisted downloader for downloading select Microsoft CTPs".
This is just another attempt by Microsoft to reinvent software that already exists in the open source space, without adding any real value to it. David Starr addressed this earlier this year in an open letter to Scott Guthrie. Examples include MSBuild (instead of nAnt), MSUnit (instead of NUnit), EntLib (instead of numerous other tools), and the list goes on and on.
When will Microsoft get that it's ok to leverage open source technology. By them leveraging and contributing, the entire development community will be better off. This is what Java has done and you dont have to look very far to see a very tight-knit development community around Java.
Interestingly enough, yesterday, Microsoft also unveiled their new web presence dedicated to their open source efforts. It's going to be very interesting to see if this new initiative helps Microsoft to embrace the many fine open source projects out there.