http://i.imgur.com/x52pgV0.png
PCSX2-CE is the easiest way to play PlayStation 2 games on your Mac, using the latest versions of PCSX2.
It's a pretty big download so it's currently hosted at GameFront:
you can download it here (updated Jan 28, 2014).
For detailed instructions on how to get it set up and working, check out
How to Install PCSX2 1.0 on Mac OS X
For advanced users:
Download the latest version of PCSX2-CE
Download XQuartz for OS X
Download the Nvidia Cg Toolkit and install it into the PCSX2-CE bundle
Use Winetricks to install Windows dependencies into the bundle:
winetricks msxml3 vcrun2010 d3dx9_36
Install the PCSX2 bios
If you have time to give it a try, I'd like to know if it works for you and if you have any suggestions on how I could make it easier to use! Right now, downloading and installing the Windows dependencies is a pain. I'm looking into how to include them in the bundle without violating any distribution rules.