there is nothing pre-built really... I made one for couple versions that wasn't entirely great.. but no one really cared much about it.... If you want to install Wine the easiest way, get and use Macports... best way to keep a good version of Xquartz and Wine running locally on your machine. there are also some other programs. I make one called Wineskin (http://wineskin.sourceforge.net) that is more geared toward making a wrapper for a windows app, to basically turn it into a Mac .app file ... its not super simple to use though... I'm working on a new version thats designed for general usage instead of just wrapper making... and I focus more on gaming, with fullscreen and resolution switching and stuff you cant do easily otherwise on the Mac. There is also WineBottler (http://winebottler.kronenberg.org/) thats more around general usage... it uses the default X11.app on your machine. I haven't used it too much, but for simple apps it seems pretty good.
