David Chartier and some other folks are worried what this will mean for the Skype user experience on Apple platforms, but they may be overstating the problem somewhat. I mean, could Skype 5 for Mac really get any worse? The Office 2011 toolbar 'ribbon' may not be terribly Mac-like, but it's aggressively functional, and whoever designed it is obviously at least competent.
Skype doesn't seem like they should be worth anywhere near the $8.5 billion in cash Microsoft is paying to acquire them. But the reason why seems pretty simple: Microsoft is scared to death of Google, who are moving aggressively into the VoIP market (with Google Voice and Google Talk) and who were reportedly another major bidder to buy Skype. This will not end well, but when faced with the prospect of a big competitor getting bigger, it's in Microsoft's nature to acquire first and ask questions later.