Mike Beltzner – the man who oversees development of Mozilla's Firefox browser – will leave the organization after the release of Firefox 4, the latest version of the browser due for official release later this quarter.

Beltzner joined Mozilla six years ago from IBM Canada and worked on six major Firefox upgrades, beginning with Firefox 1.5. "I’ve been getting antsy for the past few months, as some people may have noticed," Beltzner wrote on his personal blog, "and have decided that it’s time to challenge myself by jumping into an industry about which I know next to nothing."

After the release of Firefox 4, he's joining Dug Software, a small startup that builds geological modeling software. On Friday, with a post to a Mozilla developer mailing list, Beltzer indicated that Firefox 4 is on the verge of a release candidate. Earlier this month, Beltzner and crew released an eleventh Firefox 4 beta.

Following the debut of Firefox 4, Mozilla will move the browser to a quarterly release schedule. Typically, the outfit has released a new major version every 12 to 18 months or so, but Google has upped the ante with its 6-to-8 weeks release schedule for Chrome. ®