Campaign three appears to have a north-African theme. Enemies are believed to include tapirs and dervishes, among more far-fetched foes such as giant worms, in locations ranging from savannas littered with desert huts to Moroccan-inspired cities.
ArenaNet has stated that they will be adding two more professions to the game, however details are vague, and all that is known so far is a description of concept art from 1up.com describing the two new professions as "a white robed woman wielding a wicked looking double bladed staff, and an unarmed bald monk-like man, possibly a bare-knuckle combat class."
http://en.wikipedia.org/wiki/Guild_Wars_Nightfall
Sweet.