That looked like a pass Larry would have thrown....
The reason why that assist was special is not because it was left handed, or over the shoulder, or no-look. I would bet in a vacuum, 90% of wings and guards could make that pass.
The reason why it was special is that Rondo:
1) Was following a play to get HIM a layup, which he performed perfectly.
2) Was able to see where Ray Allen was while he entered the paint, and keep that spacial position in his mind
3) Know the positions and assignments of the 3 (THREE!) defenders that closed in on him when it became clear the play was a give and go
4) Knew how long to wait to make sure Affalo was so committed that he could not possibly close out in time on Ray Allen
5) Was able to walk away as cool as Shaft from an exploding bad-guy hideout while the ball swished through.