This is how it's going to grow? From KML in sitemap files? I have mixed feelings about this.
On the one hand, I'm very interested in seeing the Web we have now geo-enable itself. I'd love to be able to search Google (or Yahoo, or whatever) for coverages and features, and never again visit barely usable geodata portals. On the other hand, this particular approach is just another damned catalog, and one based on a single application's proprietary language.