In Mac App Store now for $29.99. Contains Orignal, Soaked, and Wild.
NOTES FOR DISC VERSION:
Works perfectly on Mac OSX Lion. To work on Lion, the app requires the update 1.2 Rev A (http://www.macgamefiles.com/detail.php?item=19285), which allows it to run without Rosetta.
Except when you download the patch, it too is a PPC app and as such can't be run.
Prior to installing the patch, make sure the app remains in it's original folder. Move the whole "Roller Coaster Tycoon 3" folder to your applications folder. Then run the patch.
In order to run the patch, right click and click on "Show Package Contents". Click "Contents" then "Resources", then double click "RollerCoaster Tycoon 3.pkg". It should work perfectly.
If you want the game to work without the CD, follow these steps.
1. download the NO-DVD Crack from the following website:
http://www.filesbay.net/file/55931-rct3-v1-2a-11332-ubcracked.html
2. Open the .dmg file
3. Replace with the RCT3 Panda icon from the crack you have downloaded. Just drag the new icon to the "Roller Coaster Tycoon 3" folder that should reside in you applications folder. Now attempt to run the game. Everything should work fine.