I wouldn't suggest using it, just because it isn't supported before the following versions:
Internet Explorer 10
Safari 6
Of course, that's just the WebDev clawing its way out of me.

I've just had to work on so many websites that have to be backwards compatible all the way back to IE 5. *shudder*
Yeah, it is, just not below those versions I mentioned.
*mumbles to self* darn backwards compatibility....
W3Schools, right?
I'm using a very simple progress bar in the APIDump, simply composed of colored <div>s, I guess it would be more than enough here, too.