Nokia have obviously had some grudges with Apple ever since the iPhone was introduced in 2007 and now they're even going to court. The reason - well, Apple have used some of Nokia's GSM, UMTS and WLAN patented technologies in all of the three generations of the iPhone, but they seem to be refusing to pay any licensing fees.
As far as we understand, the technologies in question are not a trade secret, but rather fundamental GSM, UMTS and WLAN standards, the establishment of which has taken Nokia quite some R&D time and resources. The use of these technologies has been licensed (for a fee) to all other mobile phone manufacturers since making a modern GSM handset is obviously impossible without using some of those standards (as Nokia claim).
So it's either Apple playing naughty here or their R&D department has come up with some exciting new technology that no one knows about.