Even if most of the 400 million Firefox users worldwide choose to wait for the final version, they won't have to wait long. In a message earlier this week to Firefox developers, Mozilla director of platform engineering Damon Sicore said Firefox 4 would likely be .

Mozilla hopes version 4 will boost Firefox's share of the browser market, where the program is either , depending on whose numbers you believe. October 2010 estimates from give Firefox 31.5 percent of the global browser market. However, ' data is less sanguine: Firefox's share dropped from 24.23 percent in February 2010 to 22.81 percent last month.

In addition to faster page-load and startup times, Firefox 4 promises to speed up Web apps and games, thanks to the inclusion of the speedy SpiderMonkey JavaScript engine with TraceMonkey and JägerMonkey JITs. Interface enhancements include a streamlined, less-cluttered look (i.e., similar to Google Chrome). The new Firefox button, which you click to access a drop-down menu listing all the browser commands, replaces the Menu Bar of earlier versions. The Panorama feature makes it easier to organize individual tabs. And App Tabs provides permanent tabs for sites (like Web mail) you visit all the time.

Firefox 4 supports a variety of Web standards, most notably HTML5, WebM, HD video, 3D graphic rendering with WebGL, hardware acceleration, and the Mozilla Audio API. The beta is now feature complete, the company says.