I'm trying to mount a aix/jfs filesystem on RHEL AS4. As per the man pages for mount, jfs is supported.

When I enter:
"mount homepw1:/myhome /u/" I get the following:
mount: homepw1:/myhome failed, reason given by server: Permission denied

When I enter:
"mount -t jfs homepw1:/myhome /u" I get:
mount: fs type jfs not supported by kernel

From client:
showmount -e homepw1
Export list for homepw1:
/myhome (everyone)

From server:
showmount -e
/myhome (everyone)

I am able to mount other RHEL/ext3 filesystems on this server.

Nothing interesting in /var/log/messages. Can I mount this jfs filesystem or am I spinning my wheels?

Yes, mount can mount jfs but if you don't have the driver compiled in the kernel or as a module, your stuck..
to see which filesystem your kernel knows:

cat /proc/filesystems

As it says, jfs not supported by kernel..

You have to find it as a module, if you don't want to recompile.