Mozilla CEO John Lilly dropped a bomb late yesterday in announcing that he would be stepping down from his position. The news came just after Mozilla revealed its early product plan for Firefox 4, in which it placed great emphasis on speed and HTML5 support – two of the big selling points for competing browser Google Chrome.

In fact, the news also comes as Chrome continues to steadily gain market share in the browser space. Lilly wrote a note about his pending resignation, however, that expresses his continued dedication to Mozilla and Firefox, even as he gives up the lead position. He wrote:

I’m in no rush, and the most important thing to me is to build the strongest Mozilla we can, with the best leadership possible. So my plan is to stay through that transition — we’re starting a CEO search now, and plan to do it in as transparent a way as possible — which means I’ll continue in my CEO role as normal for several more months, at least.

I’ll have more to say on the transition as we figure things out more clearly, but for now, business as usual. We’ve got Firefox 4 to ship, and Firefox on multiple mobile platforms. We’ve got our web services like Weave to stand up and make available to millions of users.

Firefox 4: fast, powerful and empowering View more presentations from Mike Beltzner.

Lilly’s heart is in funding startups, and this is the main reason he has chosen to step down from his post, according to his letter. He says he’s "always been a startup guy at heart" and that the Mozilla gig was originally supposed to be a "quick volunteer effort". He intends to join Greylock Partners as a Venture Partner, and will work on investing in startups from there.

Lilly plans to remain on Mozilla’s Board of Directors.