Google releases Google Earth API, browser plugin
You do still need to download and install a small utility though. While the plugin works with Internet Explorer and Firefox (2.0 only, Firefox 3 is not yet supported), it's not available through the Mozilla Add-ons page. The plugin is also Windows-only.
Microsoft has been offering a web-based version of its Virtual Earth application for a while now. And Poly9's FreeEarth offers web publishers a similarly custimizable spinning globe that can be embedded in web sites.
[via Google LatLong]