Yes, Its the empire march. Microsoft is suing TomTom for patent infringement in U.S. Patents:
6,175,789; 7,054,745; 6,704,032; 7,117,286; 6,202,008; vfat: 5,579,517 ; 5,758,352; and 6,256,642 .
TomTom is a European company using a gnu/linux platform. Even though TomTom is pretty large, its a pressing moment with the financial crisis for everyone. Lets hope that they can stand the pressure from Redmond.
TomTom's CEO saying that they spend more money on patent litigation than on R&D:http://www.youtube.com/watch?v=bSOIK-tlN8g
Groklaw has the complaint at http://www.groklaw.net/pdf/tomtomComplaint.pdf and a good recommendation: "Think Bilski"!
Update: Case settled out of court. Its incredible how naive most of these patents are, just watch the claims in the comments. Still they survive at the expense of development and competition. More at groklaw