If it was projectile delivered ordnance, there would probably have been gaping holes in the tables from shrapnel coming DOWN on them. The only damaged tables seem to be in the immediate blast area (which I assume to be generally under the instant skylight in the tent roof).
This would suggest that most of the frag was going HORIZONTALLY, as it would from a ground or waist-level blast.
Most of the casualties were probably secondary to fragmentation, consistant with a placed / IED weapon.
That's a lot of casualties from a body-borne bomb, but in a target rich environment like that (or a crowded Israeli Bar or Resturant) not unheard of. The MO stinks of HAMAAS, whom we are pretty sure are operating TDY in Iraq these days.
I will not be surprised if there is a connection.
FOX News is saying a "rocket" may have been fired from "miles away".... I still vote for an inside snuck-in IED.