Regarding id software they program all their software using cross platform tools such as OpenGL which allow them to offer support for all 3 major Operating systems: Linux/Mac/Windows with almost no added cost to do so above what it would take to make it for just one of those.
Anyways I do not see the big deal here seeing EA's biggest selling computer games The Sims and The Sims 2 as well as many expansion packs have already been previously released for Mac. Many games that are developed using cross platform tools such as OpenGL are ported to the Mac because of the low cost to do so and I would like to one day see more developers use cross platform tools instead of locked into one OS DirectX. One of the biggest publishers to use OpenGL is Blizzard and even on Windows you can use OpenGL instead of DirectX to run their games.
Update: It appears that EA is not porting these titles over to Mac but rather using Cider to get these games working only on Intel processor enabled Macs. Cider is Transgaming's Cedega, which is a fork of wine, ported over to Mac but for developers only and so in a nut shell if it works under Cedega any of those games can also be made to work on Mac.
There are Six games to be released which are Harry Potter and the Order of the Phoenix, Madden NFL 08, Tiger Woods PGA TOUR 08, Need for Speed Carbon, Command & Conquer 3 Tiberium Wars and Battle Field 1942. You can view the games that are already supported under Cedega on the Wiki and Forums that I have linked below.
Cider - http://www.transgaming.com/products/cider/
Wine - http://www.winehq.org/
Cedega Forums - http://www.cedega.com/forums
Unofficial Wiki - http://cedegawiki.sweetleafstudios.com/wiki/Main_Page
