It should work out of the box, also on Intel-based Mac. Nevertheless, it has been reported be that you may need to configure the tex engine after installation as reported below:
"I went to preferences->engine and in the top box, filled in what it said in the brackets (ie. /usr/local/teTeX/bin/powerpc-apple-darwin-current not /usr/texbin as was shown for some reason as the default). Note also that I did this on a powerbook g4 on Feb 11, 2007."
Before MacTeX, the best way to use ConTeXt on Mac has been [http://ii2.sourceforge.net/tex-index.html gwTeX] via [http://ii2.sourceforge.net i-Installer] so far. However, it's <b>not supported any more</b> since January 2007 (which means that you cannot post bug reports or feature requests to the author any more), but ConTeXt updates are still available and it works as expected.