Google AdSense today introduced several new features and name changes, the two most important being—

1. Multiple ad units per page. This feature closes out a round of controversy that brewed since the last update in March. Then, multiple ad units were permitted, with the requirement that the units not duplicate ads. Problem was, AdSense publishers had no way of controlling the duplication of ads. So nobody knew whether multiple units were really allowed. (I ran multiple units on some pages with no challenge from Google.) Now, Google will ensure the non-duplication of ads across multiple units. Each unit may carry a unique color scheme.

2. Collapsing ads. When Google cannot serve commercial ads to a page, the publisher may opt for an auto-collapsing ad unit to save space. No more lame public service messages, which convey this essential message: "Nobody wants to advertise on this page!"

The upshot? Expect to see a lot more Google ads, generally. Here is a discussion thread at WebmasterWorld.