I just thought it was worthwhile documenting the upgrade process I had to go through upgrading my mac from Leopard to Snow Leopard, as it was a bit of a pain.
My starting point was:
iPhone SDK 3.0.1
How I upgraded:
SDK for Leopard 3.1.2 – Note: I tried Monotouch at this point and it failed so then embarked on the following:
MonoDevelop 2.2 (beta)
Then Discovered 3.1.2 was avail
SDK for Leopard 3.1.2 (Note for young players encountered some problems because the simulator was running and was kept stopping the install – closed he simulator and all fixed)
Then all worked fine!!!!
Hope this helps