Like the overlays from Google Earth, mapplets use maps as a placeholder for geographical information. For example, you don't have to go to (the Google-owned) Panoramio's site to see photos from the entire world placed on the map, you can just select Panoramio from the My Maps tab and see the photos directly from Google Maps. Other interesting mapplets show data about earthquakes, weather, gas prices, real estate, concerts, movie showtimes, web cams, related Wikipedia articles or photos from Flickr. This way, all the Google Maps mashups could be accessible from a single interface. Google promised the developers they'll be able to monetize the mashups so they can still earn money even if people don't access their sites directly.
Even if Google Maps has a much smaller market share than Mapquest in the US, it's arguably the best platform for geomashups and Google could make it even more personal by letting you create custom maps collaboratively, placing your Gmail contacts on the map or delivering a personalized experience by selecting mapplets related to your interests. After all, Google has more users/resources than projects like Wikimapia.
