So, I got it to run on my mac (running 10.4.11) for a while (at least an hour, then I had to leave)...
How I got it to run:
Run pslaunch.app
Let it update if necessary
Push "Play"
Immediately load psclient.app (once I waited a bit, and it didn't work, it gave the same error everyone else was getting)
But... after coming back after I logged out, the next time I tried to load... something weird happened... (excuse my horrendous descriptions)
When I push "Play" in the launcher, the app closes like it should (removed from dock, as well as running applications), but the image remains displayed (without anything being clickable), and it won't let me load it again. and psclient fails to open as well... the only way to try again is to restart my computer.
Once, this same odd phenomena occurred with Safari also. (the page I was on even logged me out and refreshed, but I couldn't open/close safari, or force quit it...)
Sorry if this is of no help whatsoever, but try that sequence at the beginning and see if it lets you in.