OK, Missiles: The only air-to-ground missiles I know fire from a jet are the Maverick (anti-tank), HARM (Anti-Radar), or the ZUNI or Hydra (or variants: 2.5 to 5 inch unguided rockets). Of these, the Maverick is the most logical choice since it is guided, has a shaped-charge warhead (little collateral damage), and has great penetration.
If they hit a building with no explosive material inside, there would be an explosion outside the wall, a penetration into the building, and an exit hole on the other side. There would be casualties inside the room the missiles went through, but the buildings should still stand after wards. Obviously, the buildings were full of ammunition (high caliber like RPGs and Mortars, not just little rifle rounds) and high end explosives (SIMTEX or other plastiques). The terrorist sympathizers and cowering victims who wouldn't stand up to them just should be glad these particular "safe-houses" didn't have chemical or biological agents stored in them like Sarin or VX nerve gas (both of which would have survived the explosion and spread through the area).
Bottom line: legitimate terrorist hold-out and good targeting by our intell assets.
I could see the plane coming around for a second pass and a second missile, but I can also make a good case for one missile and a delayed secondary.
No way for me to tell which it was, but I'm sure not taking the word of any eyewitnesses.
It'll be interesting to see how much sack Zarqawi is carrying after this. Moammer Qaddafi packed it in after we got his daughter and almost got him. If Zarqawi's serious about eclipsing Bin Laden for control of radical Islam, he'll have to hit back and succeed within 24 to 48 hours.