People like to sue each other (Americans at least), and they love to sue Apple.
Supposedly, the iPhone's keyboard infringes upon a patent awarded to Florida's SP Technologies LLC in 2004. They're seeking compensation for iPhones sold, as well as an injunction against the continued "...willful and deliberate" use of their intellectual property.
We'll see where this goes. In the meantime, we'll say it again: People love to sue Apple.