if you used chaos\'s updater then do the following steps
open terminal, type in \"cd\" followed by a space, then drag your planeshift folder into the terminal, press return
then, type in:
./psclient.app/Contents/MacOS/psclient
hit return, planeshift should run now, please look at other threads before posting, there are questions like that that have been answered already, or simila quistion...
EDIT: please refer to the post \"A Guide to Running Planeshift on Mac OS X\" all amswer you need is there