Thanks to AAPF, we now know all B2/W2 Gym Leaders as they were revealed on the front page of a Pokémon B2/W2 Guide advertised on CoroCoro. The Gym Leaders are: Cheren, Homika, Shizui, Burgh, Elesa, Clay, Skyla and Drayden. Other than Elesa, the returning Gym Leaders have kept their B/W artwork. The Gym order isn’t known yet.
Update: A picture of the type effectiveness chart from the guide has been revealed and shows that Ghost-types are not resistant to Bug-type attacks anymore. Whether it’s intentional or just a printing error remains to be seen.