eZ publish 3 will of course work on MacOS, everything depends on proper environment configuration. By browsing ez.no forum you can read many topics about succussed eZ publish installations on MacOS. However for maximum performance I suggest to run eZ publish on Linux OS.
eZ publish installation how-to on MacOS
http://ez.no/community/forum/install_configuration/mac_os_x_client_howto/re_mac_os_x_client_howto__6 http://ez.no/community/forum/install_configuration/ez_publish_3_install_on_mac_os_x_v1013/re_ez_publish_3_install_on_mac_os_x_v1013
