Just as an FYI. RPM5 is used in embedded systems as well. The Yocto Project's Poky and now OpenEmbedded-Core both use the RPM5 version and not the rpm.org version.
The reason for this is fairly simple. It's been very easy to deal with, resolve and fix:
* cross compilation problems
* system level configurations
* embedded patches
Jeff occasionally complains about what he terms as "have it your own way!" configuration as being difficult and someone problematic for him as a maintainer, however this has really provided RPM5 a huge advantage when used on embedded systems. It allows us to customize the behaviors and abilities of the rpm binaries based on our system constraints.
Also above and beyond everything else, we've had the ability to actually suggest and make changes to the way things work as we've found use-cases that simply don't exist on the traditional workstation and server environments.
(Note, I'm also the maintainer of the RPM functionality in OE-Core presently... and I share a similar attitude to Per Øyvind Karlsen, I'm going to do what I think is better and what makes my job easier...)