Even though HTML5 spec is under development already, top browsers like: Safari, Opera, Chrome and FireFox have added support to most of the HTML5 specs!
If I take a look into the google Analytics of my sites, it's too sad to know that more than 80% of the users hitting my pages still uses InternetExplorer!
I believe it will be hard to beat the old MS IE browser just because most of the computers that has been and are being sold have Windows pre-installed

and so MS IE browser is pre-installed with it.
Most Windows users do not install a new browser.
The new HTML5 spec, has the video and audio tags. I don't care if they take time to decide which format to adopt, I already am using ogg and m4a encoded files, so that's really cool. The pages load faster without the need of a plug-in like Flash. I know 90% of PCs have Flash installed, but it does not work on the iPhone or the iPad.
So I'm waiting for MS to decide which format will he adopt. I hope it does not take them too long... at least not a hole year! Probably they would like to use SilverLight for video and audio, who knows!
Hopefully, Apple and Microsoft will realize that opensource formats are good for everyone. At the end of the day they could sell tools to improve the workflow (video editing software for example) or even end user solutions like google apps.
Apple should realize that if they adopt an opensource unpatented format they will still be selling a lot of iPads, iPods, iPhones and Macs. They should not try to make a propietary format a standard. The iTunes store will still be selling millions of apps every day.
Eventhough the iPhone, iPods and iPads can be jailbroken, the iTunes store still has a lot of profit, I myself has bought Apple products because I like them.
So let's promote the use of opensource for new standards, and let the end-user to choose to go for a free solution or pay for the other one.