It's generally just a matter of getting your hands on a .tmLanguage file (the same format as TextMate), and putting it somewhere in your packages directory (~/.Sublime Text 2/Packages/ on Linux).
The top Go.tmLanguage reported by Google appears to be a work in progress though, I'll see if I can get something sorted for the next version - I'd like to have Go support out of the box.
The top Go.tmLanguage reported by Google appears to be a work in progress though, I'll see if I can get something sorted for the next version - I'd like to have Go support out of the box.