Toronto Gets:
Okafor (and his monster contract)
Trevor Ariza
2013 Second Rounder
2014 First Rounder

Washington Gets:

Why Toronto?
Toronto receives a draft pick in a loaded 2014 draft, that still should be high up (wahsington will still be terrible even with Zeller/Noel/Shabazz)
- And a high second rounder doesn't hurt
- Ariza will be solid on the wing
Why Washington?

They also get rid of Okafor's huge salary
Bargnani will help a struggling offence
Calderon is a huge upgrade over price to backup often injured John Wall

Essentially Washington gets cap space (calderon expires this year) and Bargnani who if used well can be effective. Toronto gets a good defensive player and picks.
Both teams hit the reset button and hope for the best