Another feature I'd love to see in SourceTree is integration with textmate, still today one of the most popular "programmers" text editors on Mac OS X.
Ideally this would have two main functions, the first would open a repository in textmate as a new project. And the second, would be the reverse, to open a textmate project in sourcetree.
My favorite implementation of this is actually from the open source app gity (http://gityapp.com/) in that it has a menu item to open project in textmate, and this creates a new textmate project, retaining the existing source structure, etc.