PHP comes installed on OS X by default but it doesn’t come compiled with gettext support. So once you try to do something with gettext you will likely see something like this error message:
Fatal error: Call to undefined function bindtextdomain()
At this point you might be tempted to recompile PHP to add gettext but in fact there’s a better way, you can simply add it as a dynamically loaded library.
To do that download your version of php and do the following:
(inside the php directory)
MACOSXDEPLOYMENTTARGET=10.6 CFLAGS="-arch i386 -arch x86_64 -g -Os -pipe -no-cpp-precomp" CCFLAGS="-arch i386 -arch x86_64 -g -Os -pipe" CXXFLAGS="-arch i386 -arch x86_64 -g -Os -pipe" LDFLAGS="-arch i386 -arch x86_64 -bindatload" ./configure
sudo make install
When done, edit your php.ini (normally located in /etc) and add:
Next just restart apache and you should be all done.
Update: Also you can get a binary package from http://php-osx.liip.ch/