"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," said Steve Jobs, Apple's CEO. "We think competition is healthy, but competitors should create their own original technology, not steal ours."
Although the Google Android phone is not mentioned in the lawsuit, HTC makes several Android handsets, and the touchscreen models look quite a bit like the iPhone screen. HTC has not yet reacted to the lawsuit.
Apple's lawyers are busy. There is ongoing litigation with Nokia over patents and technology licensing.
For more detailed dissection of each of the patent claims, check out Engadget's post.