A lot of stuff on ia64 is only compile-tested.
This is absolutely true, but worse, a lot of stuff on ia64 is only compile-tested with GCC.
Torsten, if you've got CPU cycles to burn, you might want to grab the Intel C/C++ compiler and set up a tinderbox to go through attempting to build everything with that compiler. A lot of stuff will break, some stuff will magically work, but whatever happens, you will get _boatloads_ of warnings (many of which indicate or are related to code that isn't 64-bit clean).
Making the warnings/errors from the Intel compiler available to package maintainers would be a good first step towards 64-bit cleanliness, IMHO.
Duraid