Originally, Googlebot software was only thought to read links and parse some code, but Google told Forbes earlier today that Google now has deeper interaction with JavaScript, and its bots can even "understand some JavaScript." This could make indexing rich content a great deal easier on the world's largest search engine.
As Forbes points out, having a program understand JavaScript isn't a simple affair. No algorithm "can be applied to any program, at any point, and tell whether or not that program continues ad infinitum." However, if Google's bots could execute JavaScript themselves, it would solve some of those difficult issues.
The Googlebot is getting smarter and faster, thanks to Google Caffeine. Adding the ability to understand and even execute code in order to parse rich media may very well have been part of the update. We wonder what else the Googlebot can do now.