"As of ~4 p.m. PST today, Google Chrome 1.0+ on Windows is an officially supported browser," a Google employee said on a Google Earth mailing list on Thursday. "That means Chrome users will no longer get the unsupported browser message, and the plugin and API should work just as they would in other supported browsers."
Ultimately, Google believes Google Maps and Google Earth will converge into a single product; the plug-in is one step in that direction.
The update is also noted on the Google Earth API page from which the plug-in can be downloaded.
In other Google geography news, the company also announced a new batch of public transit map updates Thursday. Houston, Calgary in Canada, and 21 agencies in Virginia include maps and schedules, while Atlanta, Bonn in Germany, and Sacramento, Calif., among others, got maps visible through Google Transit.
(Via the unofficial Google Earth Blog.)