Acquisition discussions between Twitter and Salesforce, Microsoft and Google are frontpage news in the F.T. 

The quote below rather neatly sums up the two directions available: is Twitter for business networking or news and gossip?

The cachet is in the latter, the bankable money in the former. 

From Microsoft's point of view, it is easy to see the temptation to combine both LinkedIn and Twitter with their Dynamics CRM tools - creating a remarkable suite of both business data & business applications. You can even see a clear role for Skype in that configuration (which after the utterly botched development of that product over the past few years would surely also be a draw).

Salesforce's ambitions will be similar and they will surely be keen to lock out Microsoft. 

For Google, one suspects that the 300 million-odd general user accounts will be the carrot, adding to their array of similar tools, most notably YouTube. In this scenario, the news and gossip angle makes far more sense.