After several delays, we were beginning to wonder if Firefox 3.1 would ever see the light of day beyond a beta release, and as it turns it out, it's not going to. Instead, Mozilla has renamed the once 'fast-track' update to 3.5 with a fourth beta scheduled for April 14, 2009.

"The increase in scope represented by TraceMonkey and Private Browsing, plus the sheer volume of work that's gone into everything from video and layout to places and the plugin service make it a larger increment than we believe is reasonable to label ".1". 3.5 will help set expectations better about the amount of awesome that's packed into Shiretoko," said Mike Shaver, Mozilla's engineering VP.

Shaver went on to say that the version change to 3.5 is indicative of the current scope and not intended to represent a significant increase 3.5's current make-up.

Still no word on when the next version of Firefox will go Gold, though if we had to guess, we'd say either May or June of this year.