In a post to the Firefox planning newsgroup, Mozilla Corp’s Mike Shaver, announced that there will be at least two betas for Shiretoko, Firefox 3.1 code name.

The main reason is to allow enough time to bake a high quality private mode as announced earlier this week but some other minor but sensible changes will take place as well.

We’re still hammering out the details, but we know that there is a core list of features that we’ll be looking to land between beta 1 and beta 2, likely:

• extending TraceMonkey‘s capabilities into the DOM and other parts of our system
• completing private browsing
• a bunch of UI cleanups and improvements building on FF3′s success, and incorporating things we’ve learned from other browsers and add-ons
• some core improvements to systems like PFS [Plugin Finder System] and our security UI

Though there’s no official schedule, code freeze for Beta 1 is targeted for September’s end, so it should be around by mid-October. If Beta 2 gets to close to December, it will probably push release candidates and final release to early 2009.