My opinion is that this is nothng different than preventing another possible Alqueda from growing down there. The US probably provided intelligence and oversaw the columbians aligned the missle coordinates correctly but it was a columbian decision. My understanding is that it was a single missle.
I read that chavez was allowing the FARC to operate freely in the jungle and they had been making movements into Columbia. Columbia basically said told Chavez that if your not going to police your own territory we will do it for you to protect Columbia.
This also sends a message to Chavez, to remind him of his weaknesses. The US is Ok with you beating your chest around the world but keep your eye on your home.