10gR2 IS supported on RHEL5 (at least for x86_64.
Looking at the certification matrix for Linux on Itanium it shows the latest supported is RHEL4 Update 1 (or higher).
You have to log on to Oracle Metalink - do advanced search for the phrase "certification matrix" and the word "itanium" to find the matrix.
Since it does work on RHEL5 on x86_64 you may be able to get it working on Itanium as well but you'd have to work at it. (Actually installing even on x86_64 was a challenge because the installation docs are aimed at RHEL3 and RHEL4 but RHEL5 has some significant differences.)
Last edited by MensaWater; 11-10-2007 at 10:32 AM.