It really depends on what you want to do that isn't possible in Leopard. You haven't said what that might be. If it's something that pivots entirely around a f

It really depends on what you want to do that isn't possible in Leopard. You haven't said what that might be. If it's something that pivots entirely around a feature in Leopard, like Time Machine integration, then go for Leopard only. Otherwise, release for both Tiger and Leopard. Why not? Not everyone is using Leopard yet -- I read somewhere that the adoption so far is about half Leopard and half pre-Leopard. I'm not sure how accurate that is, but I have a hard time believing it's true. I only updated to Leopard on my main workstation about a week ago.