I've yet to personally hack around with Virtual Earth, and, coolness factor notwithstanding, I guess the ease-of-use of the API, viral marketing push for Google Maps, and expected "anything as long as it's not Microsoft" mindset is what keeps it so popular among the developer community.
Have you realized what this says about participatory journalism? This is Participatory Development! I've seen developers normally apathetic towards global events build things rapidly for mankind's benefit, just because it's the right thing to do. Any major events in the history of the world, acts of nature or otherwise, from this point on are going to be documented, archived, coded, architected, and shared through all sorts of neat apps. More impressive, mapping apps are still at the embryonic stage where the APIs aren't easy enough to tap for the neophyte to use (case in point: blogs circa 2001). Imagine the community's reaction when developing a custom web-based mapping application, obtaining geocode coordinates, dropping in a few custom pictures, an adding commentary will be as simple as point-and-click and drag-and-drop.