Grats on not only getting that drop but learning it as well! Very nice.
With such a high spirit value and two open gem slots, the Belt of Black Knowledge is great for Holy or Discipline Priests who have talents that boost healing/damage based on that stat. Come to think of it, once WOTLK talents come around it'll be wholesome for Shadow Priests as well.
It's not too shabby for Druids, either, to simply keep up with heavy Innervate gearsets.
You're partially correct on the Belt of Blasting - the pattern itself is a BoP drop from TK/SSC but the crafted item is BoE. The Nether Vortexes are BoE now too, thankfully.
For Ari it just gets down to me deciding on his primary focus on gearing… and then farming all the damn mats for 'em. >_<