While little is known about the deal, it's expected that the two companies will announce the acquisition sometimes tomorrow morning. Even more unknown is the impact that Microsoft ownership will have on Skype or how it might effect Skypes movement into the SIP and Linux spaces. It's all but certain though that development on the Linux client, which has lagged behind the Windows version since its introduction, will receive even less attention or might even be discontinued under Microsoft ownership.
This marks the third time Skype has been acquired in the last few years including what amounted to a disastrous attempt by online auction company eBay to monetize and integrate the service with their site. Ebay sold the service to a holding group a few years ago at the loss of hundreds of millions of dollars.