The title is misleading because I am pretty sure that Pro Tools is not on Linux as of yet. But good news Mactel-based audio people! DigiDesign has released Pro Tools 7.3 which is now compatible with Macs equipped with Intel processors. Pro Tools is the industry standard with audio. I know many sound designers who were not going to upgrade to the new Macs till Pro Tools became compatible.

For more info on new features, check out these video one & two (Flash video). Besides compatibility, there aren't any major new features, a lot of interface improvements. Free upgrade for existing users.