I never even realized such a thing existed, but apparently Hasbro (which now owns the Monopoly brand) had released a computer version of the famous real estate game, completely updated for 2007-- as in, there are Hybrid cars and RAZRs in the game (yeah, yeah, I'll get to that in a second), and luxury tax now costs you $150,000, instead of the quaint old $75. And it's now been released for the Mac-- you can pick it up for $20 over at Macgamestore, or grab the demo for free at Macgamefiles.
Gamespot users thought the PC version was pretty all right, so if you like the game a lot but don't always have the real opponents around to sit through the whole thing with you, this might be right up your alley.
But of course, what I'd like to see, in either virtual or realspace, is an actual Apple-branded edition of Monopoly-- the Newton and Lisa can be Mediterranean and Baltimore, and Park Place and Boardwalk get to be the iPhone and the iPod touch. You can have little Jobs and Woz figurines to move around the board (the shoe stays-- love the shoe), although I'm not sure what the railroads would be-- Apple keynotes at Mac conferences? Get on that, Hasbro!