Acacia's CEO Paul Ryan described the 74 patents as "foundational," meaning that Microsoft is trying to avoid controversy over more basic software features. Companies like Motorola have been suing recently over such earlier innovations. Other companies like RIM, Apple, Motorola, and Samsung are being sued by Acacia Research Corp. for basic features like email synchronization.
Microsoft has been making a significant effort to preempt licensing controversy. In keeping with their perfectly-prepackaged approach to Windows Phone 7, all patent fees are included, and OEMs are indemnified from patent litigation.
The GM of Intellectual Property for Microsoft, David Kaefer, provided the following general statement: "By focusing on efficiently licensing patented innovations from other companies, we're free to develop great software and we’re able to provide our partners and customers [intellectual property] peace-of-mind."
source: The Wall Street Journal via WMPoweruser