Microsoft Planning to Buy Open Source Companies?

mjasay writes "At the Web 2.0 Summit, Microsoft CEO Steve Ballmer admitted that Microsoft 'will do some buying of companies that are built around open-source products,' suggesting that to avoid open-source companies would 'take us out of the acquisition market quite dramatically.' Ballmer has apparently come a long way since dubbing Linux a 'cancer.' The real question, however, is which open-source companies make sense within the Microsoft product portfolio, both from a technology and philosophy perspective. Novell? 37Signals? Jive? SugarCRM? And, equally importantly, which companies could look their communities in the eye after selling to Microsoft?"