from the last build i could find with a quick google search, dates back to november so take this info with a pinch of salt
all classes:
every class with a +10% crit passive is getting it changed to +5% crit passive
priest:
shadow word pain 10% dmg nerf for disc/holy
mind flay new effect, causes 40% spell power as dmg to nearby enemies (assuming melee range) of your flay ticks
shaman:
unleash life getting a 8% healing increase on target not the effect
warlock: massive dmg nerf of drain soul, 66% dmg nerf and 50% healing nerf, no longer a talent just baseline affliction spell
UA dispel effect is getting a 100% dmg buff, only really affects dwarf stoneskin racial as no dispels
drain life becoming destro/demo only replacing shadow bolt, 45% spell power dmg per tick, 600% dmg as healing
mage:
losing pom (now lvl 30 talent)
fire mages getting buffs on every spell, seems to be a 10% overall buff
hunter:
not sure where the rumours are coming from but none of the spells available at 19 are getting changes, unless you can see the pvp templates somewhere