According to notes posted on the Mozilla site following a weekly progress meeting, Beta 3 will be released next Tuesday at 5 pm Eastern time. Those same notes specified a "code freeze" Tuesday at 8 pm Eastern time, indicating that developers will accept no more changes in preparation for predelivery testing.
To accommodate that fix, as well as other patches and possibly one or more new features, Mozilla has decided to insert a fourth beta into Firefox 3.1's development cycle. Previously, Shaver said it would arrive four to six weeks after Beta 3's release, which would put the follow-up beta in April 7-21 time frame.
Mozilla conceived Firefox 3.1 as a "fast track" upgrade that it originally intended to launch in late 2008. But the browser's progress has been slower than planned, and the company has reworked its schedule several times. Last November, for example, it added Beta 3 to the timetable to give developers more time to fix bugs and test features such as TraceMonkey.
This year, Mozilla first pushed back Beta 3's release in mid-January, then a week later again delayed delivery. In the interim, Mozilla had declined to set a public timetable, citing difficulties in estimating how long it would take programmers to fix several bugs.
In related news, Mozilla plans to release Firefox 3.0.7 as a security update sometime Wednesday.