Katy Perry & John Mayer: Back Together?

Like most Americans, Katy Perry hosted a Memorial Day Barbecue this past weekend at her new home. What may surprise you though is who was in attendance. None other than ex-boyfriend John Mayer. Sources at the party said the pair "seemed back together" and were "acting flirty" and "having a really good time together." Perry and Mayer broke up in March.

Are they back together or just trying to remain friendly? Do you like them as a couple?