I don’t know why this symlink is not set up after installing sublime. (Textmate does it!)
You can simply do this:
sudo ln -s /Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl /usr/local/bin/sublime
Then you should be good to go. Try typing sublime in your terminal and sublime should be launched. If not, add this line to your ~/.bash_profile file.
Or you can mess with your own $PATH variable to make it right for you.
Then next time, when you need to open up a project in a certain directory, just cd to that directory, then do “sublime .”