[AlanShutko]

You can have nested projects, and those nested projects do appear on the iPhone. That would be my suggestion.

I wouldn't use contexts for clients. Let's say on a project for a client, you have some things you can do at a computer, some at a phone, etc. If you use contexts to capture the client, you no longer have the ability to say "I'm at a phone, what tasks for all clients can I do."