The latest director of engineering at Facebook, one of four, is Mike Schroepfer - formerly VP of Engineering at Mozilla Corp. In a blog on the move, he wrote yesterday to his Mozilla colleagues: "This is the first time I’ve decided to leave something I really truly love - I will dearly miss getting a chance to work with all of you every day. Everyone that I’ve met from the community has, and will continue to be, a huge inspiration to me.”

"It really has been a singular honor to have been part of Mozilla," Schroepfer - also known as "schrep" - wrote, "and I’m hugely proud of what we’ve been able to accomplish together."

He continued:

"We’ve shipped Firefox 1.5, 2, and the amazing Firefox 3 together, taken the active users from tens of millions to >185 million in almost 50 languages, achieved 50% market share in some countries, built a thriving Add-ons ecosystem, moved into mobile, scaled our operations across the globe, and most importantly of all continued to build a thriving, passionate, talented community that is a blast to be part of.  ... I *know* that Mozilla will continue to kick butt without me - impossible to do otherwise with the strength, talent, and passion of the people here."