An anonymous reader writes "Mozilla is planning to release four new versions of its open source browser by the end of this year. That means Firefox 4, Firefox 5, Firefox 6, and Firefox 7 are all slated to ship in 2011. Mozilla was originally planning on having Firefox 4 out by the end of last year, but it had to delay the release. The last release was Beta 10 but there are still probably two more betas, at least one release candidate, and of course a final build. It's clear the company no longer thinks this model is a good one, and wants to accelerate its release cycle, much like Google did with Chrome."
More detailed information on the accelerated development cycle and the major features intended for each new version are available on Mozilla's Firefox 2011 Roadmap