From The Business Insider, March 2, 2010:

Apple today filed a lawsuit against mobile devices maker HTC. The suit claims infringement of 20 patents related to the iPhone's user interface, underlying architecture, and hardware.

In the release, Steve Jobs says, "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...We think competition is healthy, but competitors should create their own original technology, not steal ours."

Taiwan-based HTC was the first company to manufacture a cell phone based on Google's Android operating system, which has emerged as a significant competitor to the iPhone, AP reports. It's also making the Nexus One phone that Google is selling directly to consumers.

It looks like the Nexus One, and other HTC phones, may have hit too close to home for Steve Jobs.

Earlier, we supposed that Apple's multi-touch user interface could be the basis for the lawsuit. But after examining the complaint, it appears that Apple is NOT suing over multitouch, but rather a bunch of other software. (When Steve Jobs unveiled the iPhone, he touted its multitouch screen, then said, "And boy, have we patented it.")

Meanwhile, Apple is already tied up in a patent lawsuit with Nokia, claiming Nokia is stealing Apple technology. Nokia says Apple is stealing its technology. Kodak is also suing Apple claiming technology theft.

Basically, Apple's patent lawyers are going to be busy for the next year or so.

More coverage from The Business Insider: 

• 15 Features Apple Must Build Into iPhone OS 4
• 10 Burning Questions About Apple's iPad