There is a new Google Earth version available for download. It seems to solve a number of problems for my Mac including some serious crash issues with 4.0.
One of the best updates that I've noticed is the fact that the focus for UK users now starts in the UK. Non of that pointless scrabble to stop the auto zooming into the US when it launches. The UK is now officially in some patch of open moorland just north of Skipton.
Google Earth, The UK, Mac