APT is available for RPM based distributions. Developed and maintained by Brazillian Linux distributor Conectiva, but most useful on the biggest RPM based distribution - FedoraCore, nee RedHatLinux).

All you need is the tool compiled for your version of RPM and access to a repository where rpm packages and their apt MetaData can be downloaded from.

Depending on your choice of FedoraRepositories, get apt from FreshRPMs or get apt from

(Is Apt broken after installing Ximian Desktop 2? See RedHatNotes.)