There's nothing overly special about an object disappearing across an event horizon, observationally. However, blackholes happen to have extremely severe tidal forces that border the event horizon, and objects passing through this region (even stars) will be torn apart and smashed back together and will be raised to incredible temperatures and release massive amounts of energy. It is this process which is being observed, and it is actually one of the most efficient processes for converting mass to energy in the Universe.

See: http://en.wikipedia.org/wiki/Black_hole#Accretion_of_matter