Last weekend, Mozilla evangelist Christopher Blizzard showed off some of the features that will appear in the next version of Firefox at the Southern California Linux Expo.

Firefox 3.1 takes several important steps toward beefing up the browser's ability to run Web applications, one of which is that it adds support for "worker threads." These allow the browser to deal with heavier computation--if it needs to do something data-intensive, JavaScript can run in the background, while the user goes on interacting with the application as normal. This capability is very important for sophisticated Web applications and, in an impressive Firefox 3.1 demo, Blizzard showed off a browser application capable of detecting motion in a live video as it played (see the clip below). Without worker threads, there's no way that the application could have handled this without locking up.

Maybe you're not planning to run a browser application that parses the feed from your security camera? A less flashy but equally important example of the concept can be seen in the new Offline capability from Gmail Labs. Using offline mode, users can access Gmail online or off (or in "flaky connection mode," which smooths out the experience of a now-you-see-it-now-you-don't Internet connection, or a four-hour Gmail outage). One key part of the underlying technology is WorkerPool, which, like Firefox's worker threads, allows intense computation to go on in the background while the user interacts with the Gmail interface. In a conversation I had recently with Gmail product manager Todd Jackson, he explained to me that WorkerPool is what allows Gmail to perform the heavy task of coordinating the data in a user's online Gmail account with what's stored offline, without forcing the user to wait for long periods while the browser responds.

These changes are just part of a larger trend of re-engineering browsers to improve their ability to handle Web applications. Google's Chrome browser is one example of this, as is work on the W3C's HTML 5 specification, which is making great strides in standards for Web applications.