Is it possible to "upgrade" Sol10 update 9 to update 10 by booting from the DVD? I had never even tried this until a user asked me to do it, so i tried and it just hung there after the part where it reads the rules.ok file.
Is this even possible to upgrade? or does it have to be a new install.
And is downloading the latest recommended patch cluster just as good as upgrading to the next update?
Yes, you can perform an upgrade using the DVD media.
Usually I only do that when I have a mirrored disk but it's not a requisite.
Or you can use Live Upgrade, it's simpler however you'll need an additional disk in order to store the boot environment.
Most patch clusters only fix the things that are currently present on the server. They do not add new features to the OS.
Personally I don't see a lot of "breathtaking" features on U10. Here's the full list:
Oracle Solaris 10 8/11 What's New - Oracle Solaris 10 8/11 What's New
I've always missed a native chroot option, though. 
is there a reason because you have to upgrade via dvd?
liveupgrade is much simpler and can be done online!
in case you use ufs you need to have some space on the actual disk or an additional disk to upgrade...
if you have zfs you can do it by using the integrated snapshot!
what kind of filesystem are you using?
I have UFS unfortunately.
Can you point me to any documents on how to do a live upgrade on UFS filesystems? I did ZFS once before that was easy. I'm not sure about UFS tho.
ok it's a little bit complicated but possible... 
do you have enough space or an additional disk?
here a good doc:
Thanks for that doc! I found another one as well that I am using right now to do an upgrade, check this out:
I did this:
be0 = slice 0 - current running OS
be3 = slice 3 -
lucreate -c be0 -n be3 -m /:/dev/md/dsk/d10:ufs
luupgrade -u -n be3 -s /cdrom/sol_10_811_sparc/
Now, after I'm done with this, I would think that I will be booting the O/S from slice 3. How do I get it back to boot back to disk 0 after live upgrade completes? Or is it ok that I leave it to boot from slice 3? I would NOT prefer that. I would like to get back to boot off slice 0 after all is said and done.
Do I delete be0 when I'm done then create a new boot env on slice 0 to boot back to?