Mozilla team is all set to release Firefox 4.0 Beta 11 by early next week. And it is extending its beta branch to Beta 12. Maybe Firefox 4 first Release Candidate(RC) will be delayed for few days.
Microsoft has started interoperability work related to modern web standards is in no way limited to Internet Explorer 9. It has released new Windows Media Player extension for Chrome and Firefox to support H.264 videos.
Mozilla has released Firefox 4 Beta 10 and its available for download. New plan is out regarding Beta 11 and Beta 12. We may get Beta 12 before first release candidate of Firefox 4.0.
Mozilla has planned to release Firefox 4 beta 10 by January 24 and beta 11 by 31. So there will be two more betas before release candidate(RC) which is planned to release in early February.