At least one company, MoDaCo, has developed a screen shot of the UI that users can download and install as a "skin" on their PocketPC device. Apple, unsurprisingly, has not looked kindly upon these endeavors and is threatening legal action.
This likely applies to look-a-likes as well, but is more interesting as simple a casual bit of irony than of anything else. Apple isn't afraid to sue to protect its intellectual property, and yet at the same time are stepping on many other companies toes. Aggressive?