It is all googles push towards html5
Basically it creates a lot of buzz and forum posts like this pop up and you get certain people dissapointed that they can see what is happening. Hopefully it works well enough that those people quit using internet explorer and upgrade to googles chrome or another browser like firefox or safari.
Same reason that the arcade fire thing was last week and that there were the bubbles last week and that you can do the anti gravity thing and so forth.
I'm actually really happy about it all cause I hate internet explorer and have essentially quit trying to design for it entirely. If you still use it... you either work at a company that wont let you switch, or you are less intelligent. When ie9 comes out, that statement will be less valid.