I've been playing around with Solaris today, and it's just as good as I remember (except still missing all the tools I need, like Emacs). However, I was unable to NFS mount my home directory from my RHEL4 box. I would get an error like

bash-3.00# mount -o ro machine.ogre.com:/export/disk /foo/bar
nfs mount: mount: /foo/bar: Not owner

and my /var/adm/messages would have

Apr  3 22:22:36 solaris10 nfs: [ID 435675 kern.warning] WARNING: NFS server initial call to
                                               machine failed: Not owner

RHEL4 does NFS v4 (or so it thinks at least), and Solaris is not happy with something there. Obviously there must be a way to get it to work, but right now, I just needed to get it working. So, until I figure out what in NFS v4 is causing this, I decided to make Solaris just use NFS v3. There's a couple of ways to do this, easiest is to just use the vers=3 option to mount, e.g. in /etc/auto_home do something like

leif    -rw,vers=3      machine:/export/home/leif

Or, you can change the defaults in Solaris 10, by editing /etc/default/nfs, and modify

NFS_CLIENT_VERSMAX=3

After changing this default, you have to run

# svcadm refresh svc:/network/nfs/client:default

Alternatively, you could probably also disable NFS v4 on the RHEL4 box.