This is probably low on the priority list, but I think it would benefit users to differentiate the icons of Sublime Text 2 and 3. All I'm suggesting, is simply changing the color of the "S". It instantly indicates whether you are running the older or newer version. Most software companies (ahem, Adobe) justify entire updates by just changing their icon. This would just be icing on the cake for Sublime Text. But seriously, its very helpful for users.
If you have a .psd of the icon, I'd happily do it for you. I was thinking a purple S.