Here's an even bigger gotcha that people should be aware of.
There is apparently some very bad mojo that arises from a combination of the older glibc from the compat RPMs required by the Oracle install and the setting of LD_ASSUME_KERNEL to 2.4.19. Once these two things are in place, installing any RPM will cause the RPM database to be severely corrupted and unusable.
The problem is copiously described here:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=101603
But they seem to have thought they fixed it for RHEL4. Not so, as Mike can corrupt his RPM database at will just by setting LD_ASSUME_KERNEL.
This situation is relatively easy to avoid if you aren't lazy like me and don't set all your environment variables in /etc/profile. Only users who will be accessing Oracle need to have them set, and root generally isn't one of those users.
