For better or worse, wise or stupid, we run our production Oracle server on Debian (now 3.0 with kernel 2.4.19). My experience with Oracle support is that they are willing to help up until a point. Generally when I call them lots of their support people don't even ask which distribution. I just say "Linux 2.4 with glibc 2.whatever". Sometimes I add "Just like RedHat 7.[whatever version matches kernel and glibc]".
On an unrelated note that the install actually needs a patch to the root.sh file because awk is in /bin on RH and /usr/bin on Debian.
That said, I would LOVE to have Oracle certify on Debian.
Lastly, I've never had Oracle support say "sorry, we won't help you anymore since you are not on RedHat or SuSE"
