I did NY a couple of years ago and ended up in a corral about 30 mins slower than I was aiming for. A couple of things:
You leave the corral and walk in a long snake to the bottom of the bridge before the start so effectivley are out of the corral system here. There's the opportunity to politely push pass people and make up a few places.
Its fairly crowded up until Mile 4 or so, then I found it thinned out and I had space to run. This worked for me, gave me time to warm up, then settle into my pace.
I managed a PB, slighthly ahead of what I was hoping. Don't forget, although there's almost 50000 runners, you are in three waves, on three starts on roads that are twice as wide as London - there's room.
Only other thing, if you're in the Orange start I think, on the bottom of the bridge - run in the middle, not the outside 
Edited: 17/10/2012 at 12:04