I just tried installing the new PB6 version on a 10.6.4 MacBook. The installer does not know how to handle non-admin user installations, providing a write permission error on the /Applications dir. Of course this permission setting is intended as nobody in his right mind works from a root account.
Trying to install from an admins account produced permission errors, too, this time regarding the permissions to create plist config files.
Has anybody been able to install PB6 on a Mac so far and, if yes, what process did you use?