Late last week, Microsoft filed lawsuits against Motorola with the International Trade Commission (ITC) and a US federal court, alleging that the firm's Android-based smartphones infringe on Microsoft patents. The suit comes about a week before Microsoft will announce the first Windows Phone 7 devices, triggering a new battle in the mobile arena.

"Microsoft filed an action today in the International Trade Commission and in the US District Court for the Western District of Washington against Motorola for infringement of nine Microsoft patents by Motorola's Android-based smartphones," Horacio Gutierrez, corporate vice president and deputy general counsel of Intellectual Property and Licensing, said in a statement. "The patents at issue relate to a range of functionality embodied in Motorola's Android smartphone devices that are essential to the smartphone user experience, including synchronizing email, calendars, and contacts; scheduling meetings; and notifying applications of changes in signal strength and battery power."

Microsoft's suit is at least the second major legal challenge to Android, which its maker, Google, claims is "free." Microsoft argues, however, that Android is not free, given that it utilizes technologies owned by others that must be licensed. And Java owner Oracle has also sued Google over Android, which utilizes Java for its software development. Oracle seeks to block distribution of Android until the suit is settled.

Gutierrez explains Microsoft's position further in a blog post. "The Microsoft innovations at issue in this case help make smartphones 'smart'," he wrote. "Indeed, our patents relate to key features that users have come to expect from every smartphone." Covered technologies, according to Microsoft, include the ability to "receive e-mail from multiple services in real time, to read it on their phones, and to reply or send new messages out – in continuous and seamless synchronization with their email services," "manage their calendars," "maintain lists of contacts," "be notified of changes in signal strength and battery power," and the device's ability to "manage memory for storing data."

These are some pretty basic capabilities, and one might wonder why Microsoft hasn't yet sued, say, Apple for its use of these abilities in its iPhone products. Microsoft partners such as HTC, LG, and Samsung appear to be immune to such attacks as well, though it's likely that each has licensed the technology from the software giant.