PubSubHubbub. Say that three times fast. If you're not familiar with PubSubHubbub, it's an extension of the RSS and Atom protocol that allows the feed to push content out when it's updated. That's just the sort of technology we should see from check-in APIs like Foursquare and Gowalla.
Here is some interesting news that may impact developers using the Google Maps API (our Google Maps API profile). Google has recently made a couple of updates to their terms of service and have posted the the new terms of service here. There was an initial update made in early November, but one that lead to some debate and confusion about a couple of points, which in turn to a subsequent update. The net result is that the terms of service have been streamlined and some previous restrictions have been removed, including a restriction on the use of Google Maps in desktop applications. Here's a summary of the changes: