Microsoft late on Wednesday announced a deal to buy Parlano, a company that makes an online chat room application, for an undisclosed amount. 

The chat on Thursday though was whether Microsoft was looking at something much, much bigger — such as Research in Motion Ltd (RIM), the company that makes addictive email device the Blackberry.

Microsoft has been an active player in the M&A boom this year. In May, it announced its biggest acquisition ever with the $6 billion buy of Web advertising firm aQuantive Inc. Other deals it has done include July’s acquisition of AdECN, a stock market for buyers and sellers of Web advertising, May’s acquisition of a 4 percent stake in online jobs site CareerBuilder.com, and a deal in March to buy privately held speech technology company Tellme Networks Inc, valued at about $800 million according to sources at the time.

Then there is the shortlist of companies it’s been speculated to have be interested in — everything from Facebook (privately owned) to Yahoo (publicly traded), to Dow Jones (which has agreed to be bought by NewsCorp). Add to that list RIM, a rumor that keeps rearing its head. 

Microsoft can afford such a big appetite because of its high level of cash generation — it bought aQuantive for cash, rather than stock. But buying RIM would be another ball game - the company’s market value is more than $40 billion. 

To be sure, the RIM/Microsoft speculation isn’t new.  But would Microsoft, valued at around $260 billion, have the hunger for such a big deal? Reuters put that question to Rodd Langenhagen , managing director at Revolution Partners, which advised Parlano on yesterday’s sale to Microsoft.

“aQuantive was a huge deal by Microsoft’s standards,” said Langenhagen. “To see them do another would be a bit of a surprise, for sure. But with aQuantive they proved they’re willing to do billion dollar deals.”

Microsoft itself has indicated it wouldn’t rule out big deals. Chief executive Steve Ballmer in May said larger deals were “conceivable” but declined to comment when asked to drill down on size.  

Langenhagen added that while it would be out of character for Microsoft to look at a deal the size of RIM,  there are only a handful of buyers that could afford to buy the Blackberry maker. “So for nearly anybody it would be almost out of character,” he said.

Langenhagen sees Microsoft remaining on the hunt, though. “While this acquisition (Parlano) is key to protecting their core revenue base — the office communications base — Google is encroaching upon them… and they will continue to need to look for ways to more actively address on-demand applications and advertising-supported models.”