Recently, Google announced their change of AdSense program politics. One of the most important changes for ad publishers is the opportunity to put three (3) link units on their page and not only one, as it was before. Overall, this means that you’ll be able to put on a page:
three link units
three advertisement units
two search boxes
As for the search results - the rules are the same. Only one advertisement field and no changing of the code whatsoever.
What I think
Link units are a great source of filling up empty fields in your design with useful, targeted links. Good for the visitors and good for your wallet. Thanks for the change, Google