I just test PokerTH 0.6 for mac.
On my iMac intel it works fine (10.4.11)

But on my old PowerMac G4 (10.3.9) it crash at startup with this message at the "console" :
-----------------------------------
Avatar directory does not exist.
Avatar directory does not exist.
terminate called after throwing an instance of 'boost::filesystem::basic_filesystem_error<boost::filesystem::basic_path<std:tring, boost::filesystem:ath_traits> >'
what(): boost::filesystem::basic_directory_iterator increment
-----------------------------------

There is 2 "avatar" directory in the package at "Content:Resourcesata:gfx:avatars:default" including 2 sub-dir : "misc" and "people".

I suspect the directory where i put the game, called "• Jeux" (with a strange character fist), so i move the application to my desktop.
The game still fail to launch, but the error was shorter then :
-----------------------------------
terminate called after throwing an instance of 'boost::filesystem::basic_filesystem_error<boost::filesystem::basic_path<std:tring, boost::filesystem:ath_traits> >'
what(): boost::filesystem::basic_directory_iterator increment
-----------------------------------

This might be related to a charset problem. Does your username contain special (non-ascii) characters?

If not, it seems that there is no solution at the moment. It might be that boost filesystem is not compatible to your version of MacOS. And boost filesystem exceptions cannot be caught on MacOS - I've reported this problem
http://www.nabble.com/boost-3A-3Afilesystem-exception-not-caught-on-MacOS-X-to13931648.html

but there is no fix, so it is not possible to ignore this error and play without avatars. Sorry.