Google defends its position regarding WebM and HTML5:
http://blog.chromium.org/2011/01/mor...deo-codec.html

Woah! Google will be releasing a plugin for IE and Safari to support WebM in those ecosystems.

With Flash planning support for WebM as well, developers will be able to use WebM worry free and target ALL MAJOR MODERN BROWSERS using Javascript to launch a flash player in its absence, or requiring that the user download and install a plugin.

That's a 'mate' move, and one exceptionally well played by Google.

What now remains is for Google to educate developers to use WebM as their codec of choice. Web developers will determine the winner.