then you should see google in silver letters and when you begin typing they should change color.
If not, you need to delete your temporary internet files or something cause if you are on chrome it supports html5.
Anyway, it is a ploy to promote html5 which is awesomeness. I support their efforts.
It probably wont be permanent, my guess is they are going to keep changing it periodically so that people can see more of what html5 has to offer.