Curious if a barbarian's Howl of Fury provokes opportunity attacks, as it does not specify CLOSE blast. I think it's reasonable to assume it does not?
No, Howl of Fury does not provoke OAs.
From Primal Power, p11 (emphasis mine):
You provoke OAs by making ranged or area attacks (not melee or close attacks). Howl of Fury is a melee attack (it happens to affect a blast, but it's still a melee attack). Therefore Howl of Fury does not provoke OAs.