[Lizard]

I can't really recommend a single OmniFocus database for multiple users. A better solution would be a tight integration between OmniPlan and OmniFocus (which we're working on).

While you could use OmniFocus syncing the way Saaby describes, you'd lose data frequently if you both make changes to the same tasks at close to the same time. There's also no way in OmniFocus to see who made what changes when. And no way to keep your assistant from accessing all your projects.

I think you'd find that using OmniFocus with a shared database would be forcing a round peg into a square hole.