Google Lat-Long has the announcement, Google Earth Blog reports from the conference and adds details, and if you have a Windows machine, rush to download the plugin at the Google Earth API page, peruse the developer’s guide, then check out some samples. Here is Google’s intro video:
How many minutes before the first 3D Google Maps mashups are released in the wild? If you find some, do post to the comments.
[Update 16:51 UTC: O'Reilly Radar has more context.]
[Update 17:18 UTC: Barry Hunter has some demos up on nearby.org.uk.]
[Update 18:12 UTC: Dan Catt looks under the hood of the new Google Earth API and likes what he sees. Separately, the Mac version of the Google Earth plugin could arrive within two months, I've been told.]