[skwirl]

This isn't possible in OmniPlan right now. We do have a feature request for this in our database which I'll add another vote to for you.

In the mean time, you could create one OmniPlan project file and add each project as a group in OmniPlan. That way, you could put all the tasks associated with each project in the appropriate groups and still be able to track your resource schedules and see potential conflicts.