I know there has been some discussion of installing Snow Leopard (SL) on a newly purchased 2010 Mac Pro that now comes shipped with Lion. I had to do a lot of legwork to come up with an actually very easy solution. I HAVE to have Rosetta and for Apple to not include this with Lion is truly unconscionable. I and many other make user have programs that we use every day that are not Intel.
Apple cannot tell you that you can install SL but it is actually very easy. Here is what I did:
When I received my brand new Mac Pro (MP) 3.33 (2010 model), I swapped out the main drive with an OWC Mercury 3G 240 SSD. I put my Lion drive to the side. I then booted the MP in target mode (just retsrt and hold down the "T" key). When booted into target mode, I plugged it into my Intel Mac Book Pro. You can use any Intel Mac though. I then plugged the MP into the Mac Book and the MP SSD showed up on the Mac Book Desktop. I reformatted the drive (1 partion but you can have more) and installed the SL 10.6.3 install disk into the Mac Book. I told the installer to install the drive on the newly formatted SSD that is present on my Mac Pro desktop. I installed SL to this target drive with no problem. The computer then restarted -- this is standard so don't be alarmed like I was. Once rebooted, I went through the first time user process I then installed the SL 10.6.8 Combo updater to the SSD.
I was then able to boot into the MP with no problems. To be safe, I then re-ran the 10.6.8 Combo updater and restarted. I then installed all the other updates for SL 10.6.8. I repaired permissions and that was that. DONE!
Now my brand new (1 week old delivered on 4/10/2012) MP 3.33 is FLYING with SL 10.6.8, an OWC SSD and Rosetta. I could not be happier!!
I have the Lion drive as a back up or if I need to call Applecare.
Please tell me if you have any question