We are currently running gw7 on oes2sp3 (sles10sp4), 64 bit. On the
fence right now about moving to oes11 when we upgrade to GW2012.

Got some info about messenger from Novell, looks like it can be on a GW
server if it's not "too busy". Our primary GW server has a post office
about 80 GB on nss, about 200 users on this post office.

Never does seem overly busy, aside from during the backups, etc.
Wondering if it would be safe to install messenger on this box that
would potentially have possibly over 600 users able to connect on
messenger, or if I should just look at a server just for messenger.

Per Novell, the messenger agent is mainly network intensive, so the
disk i/o should not be an issue, just wouldn't want to start bogging
this GW server down network-wise.