They have a great opportunity to twist Microsoft's arm with HTML5. Chrome's the fastest browser out there now, and it will be the only option on some devices (ChromeOS/Android). Also, if the Firefox folks don't have the manpower/funding for a good HTML5 implementation, it will be no skin off Google's back to help them out. So, if MSFT doesn't come up with a good implementation in IE9/10/whatever, they risk being the odd man out ["For best results, use Firefox, Chrome, or another HTML5-compliant browser for this site."] Microsoft would have no choice but to completely concede the user experience to an abstraction layer built on top of its cash cow.

And, what chips has Google actually put on the table? One thing might be that they aren't putting out a set of Open Source but non-standard plugins for Chrome/Firefox/IE to replace Flash. Google is implicitly taking the risk that Adobe will implicitly own the web if more and more sites standardize on Flash-based stuff. Perhaps, since it's more likely that the world will rally around HTML5 than around Google's Flash competitor (or Silverlight), Google is actually adopting a least-risk strategy?

Also, for all we know, Google has a set of plugins waiting in the wings should HTML5 die on the vine. It was rumored that Microsoft had a version of Office for Linux ready to go should the desktop market tip so heavily out of its favor that it risked losing its Office semi-monopoly if it didn't support Linux.