PennApic member Dave Craley, had this situation in his bee yard on October 2, 2011. This cluster had been sitting on the front of the hive for several days. The weather has been rainy and cold. Some of the bees had started falling off the cluster, and probably started starving to death. There is probably a queen inside this cluster. A castoff of possibly a two queen hive.
Dave installed a shim on top of the second box, allowing the bees an upper entrance. The bees used this entrance to access the hive and over several hours, all went back in the hive. Hopefully, the bees will determine which queen will take over the hive.
Combining the bees back inside the hives was probably best. It is too late in the season to start a new colony. Thank you Dave for sharing this experience and allowing others to see this event.