The ga.js code offers Event Tracking, a feature that tracks "events" that don't necessarily generate new pageviews. Embedding this code will
give you detailed data on things like users dragging-and-dropping on a Google Map, clicking on buttons or images and other AJAX or Flash-based actions.
Minteer cautions site owners that ga.js is not compatible with the previous tracking code, "urchin.js"---so if you use the new code on one page, you'll need to upgrade to it everywhere else on your site.