The U.S. was prepared to take alleged arms dealer Victor Bout to the U.S. to face charges when they hit a snag. Shortly before the Appeals Court ruling that opened the door to extradite Bout, the Thai government filed another extradition request for additional charges, including money laundering. This was likely an insurance policy in case the Appeal Court had ruled against the U.S.
Well, the insurance has complicated things. The U.S. had up to three months to extradite Bout, but a plane showed up within a week to take the Russian to a comfy U.S. jail cell. I can certainly understand the U.S. eagerness to get Bout to the U.S. Accidents can happen anywhere, and with a high profile guy like Bout, one doesn't want to take chances.
So when the U.S. showed up and said "ready to take him", the Thai authorities threw up their hands and said "not so fast". It seems that it is against Thai law to allow Bout to leave until all the extradition charges against him have been decided or dropped. It boils down to the fact that the U.S. cannot take Bout back to the U.S. because there is a pending case against Bout that could result in his extradition to the U.S. Yeah, the law always makes sense.
The U.S. has requested that the Thai government drop the new charges against Bout. It makes sense that the Thai government would comply, as the additional charges were filed on behalf of the U.S., and involve crimes that violate U.S. laws. The Thai government probably will, however, this is Thailand, and you can never be sure until its done.