[whpalmer4]

If you want them all to live in the same database, the answer is currently no. Everything gets synced everywhere, and there are no access controls once you have access to the database.

Now, if you are willing to go to some trouble, you could have a separate user account with a separate OmniFocus database, syncing to a different MobileMe account or one of the free options such as SwissDisk, and you could put the sensitive stuff there. You would lose the ability to have all of your projects in a single view, however.