Yes–we love our filters! Just go to the "Filter Guests" dropdown and you can filter by "Definitely Invited," "Maybe Invited," "Missing Information," or "Relationship to You."
Within the Track RSVPs tab, you can also filter by by guests who have not RSVPed yet. Select All by clicking on the check box above guests, and then perform a Bulk Action like "Send Message" to just those who have or haven't RSVPed.