Maybe Microsoft liked Niels Hartvigs plan to move their framwork towards MVC.

Personaly I think they needed content localization and workflow.

"Microsoft is pushing Open Source, thus the move away from Community Server.?"

If they liked Community Server, they could have easily had the source for it through a deal. I am sure Telligent will be happy to get the exposure from Microsoft using its software.

Open source as a reason for the site, maybe. Open source as a new religion at Microsoft, certainly not. It's still a company making money from closed source. Maybe MS has some open source projects but certainly not pushing it. Deep inside it I am sure it resents it, but it's trying to look good in the public eye.

Are you making a statement because you actual know from them or are you just guessing because it makes sense??

One criteria I use to evaluate a forum software is its search capabilities.. Umbraco's forum search has a single search button. No advanced search or even a help link. No filtering capabilties. You can't filter by forum, by date range, by author, by boolean filtering (some words, all words, exclude) or by if posts have replies. I  wasn't impressed.