Aperture Incompatibility?

I installed Snow Leopard quite a while ago, and installed the latest updates. However, Aperture won't open, with the error message "You can't use this version of the application Aperture with this version of Mac OS X. You have Aperture 1.5.6" (I don't understand why there's the happy Mac smile there even though it's an error message.) So does this mean that Apple is forcing people to upgrade to Aperture 2, or if they are releasing an update for this soon? And does anyone else know of a list of applications that might have compatibility problems? Thank you.