We've just shipped Unity 2.6.1 out to the world. This release includes a Webplayer that is compatible with 64-bit Safari on Snow Leopard, and fixes for problems affecting terrain trees and some asset importing. This upgrade is recommended for all users.
You can see all the good stuff here: http://unity3d.com/unity/whats-new/unity-2.6#unity-2.6.1
And download the latest build here: http://unity3d.com/unity/download/