As reported by the Digital Earth Blog and Google Earth Blog, the Google Earth plug-in now works in Firefox 3! This was a silent update, as you don’t even need to update your plug-in — it simply works. Presumably some code on the backend has been updated.
Updating browser plug-ins can be a pain, and I was worried that we’d be seeing a lot of them from Google as they get the plug-in fixed up. However, this will be quite nice if they can do most of the updating remotely and not require users to update the plugin themselves.