[citation][nom]aberchonbie[/nom]We don't know the amount of money involved in development, distribution, management, and marketing spent on the steam client/games for Mac now, but I really question if it's worth it since there really aren't a huge amount of people using Macs compared to PC's.[/citation]
A couple months back, Direct2Drive was having a Mac sale at their website. Dragon Age: Origins was one of the games on sale at 50% (!) off the original price, while PC gamers were stuck with the full price. I emailed D2D asking them if this was the type of promo their customers could come to expect in the future, and I was told (more or less) that since Apple gamers are slowly taking a larger chunk of the market, we will be seeing more and more promo sales catered to Mac gamers. When I questioned why Mac users were getting a much better deal than PCers, the CS rep claimed that Mac sales for DA: Origins were pretty significant, even compared to PC sales (complete b.s. IMO, but whatever).
Up to that point, I had never seen DA: Origins available at that price for PC gamers, either at D2D or at any other digital distributor. Keep in mind that DA: Origins wasn't released for the Mac until almost a month after the original PC release date. This just reiterates the point I made in my earlier post: the more popular Mac gaming gets, the more excuses studios will have to shaft PC gamers on price (not to mention quality).
For the foreseeable future, I don't see the Apple gaming "explosion" as having anything but a negative effect on the PC games market.