I've asked everyone from the mac store to Apple Care...no one knows. I don't want to buy a leopard computer from my friend if it won't work, and I don't want to update to snow leopard.
There is a current Leopard SDK, v 3.1. Works fine on the latest hardware. Xcode on Leopard doesn't have all the features that Xcode on SL does but the SDK works with the latest iPhone OS version.