Mike Beltzner - the person who oversees growth and development of Mozilla's Firefox browser - will leave the company following the release of Firefox 4, the newest version of the browser due for official release later this quarter.

Beltzner joined Mozilla six years ago from IBM Canada and done six key Firefox upgrades, beginning with Firefox 1.5. "I’ve been acquiring antsy for the last couple of months, as some folks might have noticed," Beltzner wrote on his personal blog, "and decided that it’s time to confront myself by shifting into an industry about which I know next to nothing."

After the release of Firefox 4, he's joining Dug Software, a tiny start-up that constructs ecological modelling software. On Friday, with a post to Mozilla developer mailing list, Beltzer indicated that Firefox 4 is on the verge of a release candidate. Earlier this year, Beltzner and crew unconfined 11th Firefox 4 beta.

Subsequent to the debut of Firefox 4, Mozilla is going to move the browser to some quarterly release schedule. Generally, the outfit has released a new main version every 12 to 18 months or so, but Google has upped the ante with its 6-to-8 weeks release schedule agenda for Chrome.