Here’s the creative pitch:
It stands strong and true, resilient and universal as the markup you write. It shines as bright and as bold as the forward-thinking, dedicated web developers you are. It’s the standard’s standard, a pennant for progress. And it certainly doesn’t use tables for layout.
And here’s a bit more useful background information, provided by Ian Jacobs:
A number of people have already asked me “What does the logo represent?”
We intend for it to be an all-purpose banner for HTML5, CSS, SVG, WOFF, and other technologies that constitute an open web platform. The logo does not have a specific meaning; it is not meant to imply conformance or validity, for example.
The logo represents “the Web platform” in a very general sense.
Seriously, what do you think about the logo?