Mozilla, get it together. The open source foundation adds yet another beta to Firefox 3.1’s development cycle. Final release is now more than three months away.

Beta three of Firefox 3.1 will be released next week, come hell or high water (or, more likely, lots of bugs), says Mozilla.

But due to problems with the new TraceMonkey JavaScript engine, Mozilla has added a fourth beta version, which will come out in around seven weeks.

Firefox 3.1 has undergone a succession of delays since October.

Since then, Fox fans have tapped their keyboards helplessly as Google released Chrome, Microsoft its IE 8 and, now Apple unleashed the all-singing, all-dancing Safari 4 – all bar Chrome are still in beta, yet mostly stable, unlike the flaky Firefox 3.1.

Apple, in particular, has been stealing market share.

TraceMonkey represents a ground-up re-write of Firefox’s JavaScript engine, a project designed to keep Mozilla competitive in the browser speed war against Chrome, with its heavy JavaScript focus, and now Apple, with Safari 4 powered by its new Nitro JavaScript engine.

Mozilla has also drawn flack recently with a seemingly unworkable alpha version of Firefox Mobile, aka Firefox Fennec.