mostly the G minor pentatonic scale and Bb major pentatonic scale (which are the same thing), if you take it in context of the chords (Ebmaj7 and Bbmaj7)
sometimes he goes intot the Bb minor pentatonic and blues scale
since ur interested JM's soloing, do u kno he had a side project John Mayer Trio? They wrote n covered lotsa blues stuffs. Really cool. I think he's the SRV of our generation...