To answer some of the speculations that were brought up - the partnership will create a Skype widget within Facebook (not necessarily the desktop tool that was mentioned), allowing two people to talk face-to-face (not the 'big party' some were hoping for).
The widget does not require Facebook users to download a specific service from Skype before video calling each other. Users can instead download a plug-in for the video chat tool, which takes between 10 and 20 seconds, in order to start talking face-to-face.
Although this definitly means great things for Facebook, and further enhancement of their social mission of connection, I wonder how will this translate specifically to advertisers on the network? Do you really think people would be able to chat with a representative of a company they "Like" for instance? That will require memebers of different companies to be part of your chat display which I don't think is the case right now.
But since I know Skype does advertise, and different ads do pop-up when I skype with people, I am sure the same method could be applied to the Facebook-new-video-chat.