Japanese blog Macotakara has uncovered documents published on Access (formerly PalmSource) that show Apple has licensed US$10 million worth of patents from a number of former technology companies, including the now defunct Palm. Interestingly, as 9to5Mac points out, Steve Jobs once told then Palm CEO Ed Colligan in an email exchange that Palm's patents were essentially worthless.
There's not much word on what patents were licensed, but given that they "only" cost $10 million, they probably don't represent groundbreaking tech. The announcement letter refers to the patents as "foundational patents." Microsoft reportedly licensed the patents as well.