You could, but an RPS with a custom kernel is not very good because it has to load it from the SAN. Which takes along time, maybe 30 minutes before the server will boot.
The OVH Kernel, bring security and drivers mainly, but you can compile your own with our config file,
ftp://ftp.ovh.net/made-in-ovh/bzImage/2.6.34-2/
The kernels should be live in the next 48 hours, which then should allow you to upgrade from 9.04, 9.10 to 10.04 - but we need to check first, you might need to run 1 or 2 commands.
A new build of 10.04 for the RPS is probably a few months away...