Mozilla, Opera (and Google) aren't the only ones supporting the open-sourced VP8 video codec in their browsers. Microsoft is going to do the same, as well, according to my tipsters.

Update: It seems like the tipsters were on the money. See below for Microsoft's latest codec-support statement.

(I don't know exactly when or how Microsoft is going to support VP8 with Internet Explorer. But given IE 9 is unlikely to ship until 2011, according to various sources of mine, the Redmondians have some time to figure it out.)

At the Google I/O conference on May 19, Mozilla and Opera announced with much fanfare their plans to support VP8 codec, which Google acquired when it bought On2 Technology. At the I/O confab, Google unveiled the WebM container, which includes VP8 video and Ogg Vorbis audio support. (Google officials said WebM will work well on even lower-power devices, including netbooks and handhelds, according to Engadget.) WebM is going to be available under a royalty-free BSD open-source license.

At the end of April, Microsoft IE General Manager Dean Hachamovitch created a bit of controversy when he blogged that IE 9 would support the H.264 codec only. In an update to his comments, Hachamovitch said IE 9 users will, of course, be free to download and install other codecs. But the implication was that IE 9 would include built-in support for H.264 only.

(A related aside: My ZDNet colleague Ed Bott did a must-read post that rebutted the notion that H.264 codecs might end up a costly proposition for consumers, as opposed to the open-sourced VP8.)

I've asked Microsoft whether the company is, indeed, going to add VP8 support to IE9, but have yet to hear back.

This just in: Microsoft is confirming it will support VP8 via a just-published blog post from Hachamovitch. The bottom line:

"When it comes to video and HTML5, we’re all in. In its HTML5 support, IE9 will support playback of H.264 video as well as VP8 video when the user has installed a VP8 codec on Windows."

Hachamovitch does note in the May 18 post that Microsoft still considers H.264 to be the superior video codec choice. From his post:

"Today, hardware support is widely available for H.264 both on PCs and phones. (You can read about the benefits of hardware acceleration here, or see an example of the benefits at the 26:35 mark here.) Codecs have been a source of security and reliability issues (link1, link2, link3, link4) for some users. New code often faces security issues; the H.264 codec in Windows 7 has been in broad use for some time now. Sites also need to think about the issues in supporting multiple formats."

I've also asked the Silverlight team what its plans are, going forward, in terms of VP8 support. At the Google I/O conference today, Adobe officials said they are going to put the VP8 code into the Flash player and push it out to "a billion users within a year" (as News.com's Stephen Shankland tweeted).

No word back yet from the Silverlight spokesperson. I'll update this post with any Microsoft comments I get.

More just in: I didn't get a direct response to my question, but here's Microsoft's statement regarding VP8 and Silverlight:

"Silverlight today supports H.264, VC1 and other audio-related codecs, Also, the Raw AV pipeline makes it easy to support a variety codecs."

Meanwhile, I wonder how/if Apple is going to support VP8 on the iPad... Any guesses?