Welcome to the mobile patent wars, Barnes and Noble! It's a unfortunately rite of passage for anyone with a phone or tablet, and it was really only a matter of time before Nook caught somebody's stink-eye. Specifically, Microsoft's.

Microsoft filed legal actions with the ITC today against B&N for patent violations similar to those cited in the company's Motorola suit last October. According to today's official release:

"The Android platform infringes a number of Microsoft's patents, and companies manufacturing and shipping Android devices must respect our intellectual property rights. To facilitate that we have established an industry-wide patent licensing program for Android device manufacturers," said Horacio Gutierrez, Corporate Vice President and Deputy General Counsel for Intellectual Property & Licensing.... "we have tried for over a year to reach licensing agreements with Barnes & Noble, Foxconn and Inventec. Their refusals to take licenses leave us no choice but to bring legal action to defend our innovations and fulfill our responsibility to our customers, partners, and shareholders to safeguard the billions of dollars we invest each year to bring great software products and services to market."

Foxconn and Inventec are also named in the filing.

Microsoft won't have a serious dog in the tablet fight until the end of 2012. But who needs products when you can sue for licensing fees? [Microsoft]