As the rumors started flying around the internet from yesterday, everybody started digging information about Microsoft buying Yammer, the enterprise social network provider. Now WSJ reports that according to their sources, Yammer Inc. has agreed to sell itself to Microsoft Corp. for more than $1 billion. Still there are no clear details on when the deal will be announced, etc,. Also Microsoft is hosting a major announcement on Monday at LA. It could be the announcement for Yammer acquisition too.