Presumably they made something interesting with nice design. The bar isn't that high--TechCrunch covers very early Web 2.0 startups. If you write to them, and your site is worth a crap and in an interesting space for them, they'll probably cover it. It does help to be in the Valley and actually run into a TC writer in person (they're all really nice folks, in my limited experience), but it's obviously not mandatory.