Since Lenny was the first Debian release to feature CUPS under its new package naming strategy, I started going through 'rdepends' results to see which packages in Squeeze still present dependencies for *cupsys* packages.
Much to my amazement, there's quite many.
If you are the maintainer of a package that still has those dependencies, please fix them ASAP. Alternately, if you're aware of any favorite package that does, please do not hesitate at filing a patch to help the maintainer update their debian/control.
Comes June 2009, transitional CUPS packages will be removed from our debian/control.