Is there a way to limit visibility to a confidential project, perhaps only to the project owner and project team?

Under Project actions, you have the ability to limit sharing of the project to specific teams and/or individuals. Hope that helps.

Hi Pamela - go into the project sharing and remove Inherited Permissions from the project, it should only be the owner, project team, and of course system admins.

One thing, also check the People/Staffing area (not sure which interface you are using) and remove any access people as well.