There are definitely a few scams!
http://macholdem.net has a list of
poker rooms that are compatible with the Mac. If you have a good
read, it becomes clear pretty quickly that, for the Mac, not all game
are equal! the best ones are those with full software, not 'Flash'
browser games.
Check out http://macholdem.net and pay attention to the sections that
tell you what system each site works on...