Springs, I'm just the opposite: I know the end, but rarely consciously know what I'm writing about until half way through. This often means a ton of rewriting, but usually the end survives.
The great advantage with starting at the end is that everything you add before the end is essential to the plot - you won't have any loose ends plotwise, just sort of trailing off and being forgotten. You might have the opposite - Starting off with a plethora of loose beginnings (just like most books seem to do, in fact)
'And then everything explodes!' However, I rarely keep it