When Steve Jobs and company introduced the iPhone three years ago, they emphasized how they'd patent the heck out of many of the underlying technologies that make the smartphone tick. Today, Apple backed up that assertion with the announcement of a lawsuit against Taiwan's HTC for infringing on 20 Apple patents related to the iPhone's user interface, underlying architecture and hardware.

HTC is the leading provider of Windows Mobile and Android-run smartphones. It even built Google's Nexus One for the search giant. HTC offers a proprietary touch interface that it installs above the main operating system for many of its handsets.

"We can sit by and watch competitors steal our patented inventions, or we can do something about it. We've decided to do something about it," Apple CEO Steve Job as statement. "We think competition is healthy, but competitors should create their own original technology, not steal ours."

Apple filed the suit against HTC concurrently with the U.S. International Trade Commission (ITC) and in U.S. District Court in Delaware. HTC has not publicly replied to the lawsuit yet.

In addition to the new tussle with HTC, Apple is currently in a legal tangle with Nokia over patents, which each company suing the other.

Cupertino's shipped over 40 million iPhones so far and the App Store now contains over 150,000 mobile applications.