Hey

I had the exactly same issue, pd won't launch at all. I couldn't find any proper solution except people reinstalling mac os x to get it working.

The error in the console is: ERROR: failed to allocate port, exiting!

That comes from people changing the configuration in /etc/hosts
Pd needs the line: 127.0.0.1 localhost
and it solves port allocation and pd finally start!

Hope it helps (and it probably is the same issue that some people are having with Lion)