I found this cool desktop notification feature in the stackoverflow chat.
When I click "enable desktop notification" it says "Desktop notification is blocked by your browser; help me with this". There is no help for Safari. I allowed notifications for chat.stackoverflow.com in the settings. The notifications should appear in the OS X notification center ...
I'm using Safari 6 on OS X 10.8.1.
It's seems to work in Chrome, but not in Safari.