The official Google blog explains why the Google Earth site lost its “beta” sign a few minutes ago:

Our eldest, Google Earth for the PC, is officially leaving beta status today, and we couldn’t be more pleased. For those of you who downloaded early, upgrade to the latest and discover Google Earth all over again.

[Update 21.27 UTC: Frank notes on Google Earth Blog that the current version for the PC released November 18, version 3.0.0762, has been rechristened as the first non-beta.]