Most of the important stuff for Zerg involves Mutalisks regenerating more quickly when left alone, and Infestors' Fungal Growth now being a projectile (and thus dodgable). Swarm Hosts haven't really found much play yet.
Sakurazaki covered most of Terran, but in addition to Widow Mine drops, drop play in general is more viable due to Afterburners (TurboVac!), and Widow Mines are usable as limited map control. Hellbats are inexplicably biological, so they can be included in a bio army and healed by Medivacs while maintaining the front line with fairly strong HP and great anti-light splash damage. They're also pretty decent at supporting Siege Tanks for mech play. Hellbat/Thor can kinda work in TvP.
Protoss' biggest changes include Oracles, which can provide a fairly meaningful early-midgame harass; Mothership Core; and the updated Void Rays (they no longer charge over time, but can instead temporarily supercharge their beams to WoL full power) making VR/Colossus the new Ball of Death to beat. Actually yeah, a lot of Protoss air has seen updates now.