We use Sublime Text everyday and got tired of seeing the old icon. For this reason we designed our own along with icons for different filetypes that we use.
If you are interested in using these icons you can download them here: http://wearegoat.com/files/SublimeText-Icons.zip
Or you can clone it from GitHub: https://github.com/wearegoat/sublime-text-icons
To change the icons of your filetypes go to Applications and right click on Sublime Text > Click "Show Package Contents" > Contents > Resources and move the icon files into that folder.
To change the icon for Sublime Text just open up the info panel of the SublimeText-icon file, click on the icon and press ⌘+C, go to applications and open up the into panel of Sublime Text, click on the icon and press ⌘+V.
We've also included the AI file in the ZIP folder just in case you want to create your own for any filetype we didn't include.