To the OP. It's just a gimmick. Joey's right.
By the way, the method isn't poaching -- but a cross between half-a$$ed sous vide and en papillote.
If you're interested in doing fish that isn't the same ol' same ol' you could do worse than fooking around with wrapping (en papillote). There are a lot of opportunities to play with what other things besides the fish go in the packet. You just have to be very careful about time and temp, because -- since the fish is wrapped -- you can't see or feel it to test for doneness.
Parchment looks better than foil, but it costs more and it's a bigger PITA to get a good seal on a parchement packet than foil.
Either way, opening the papillote and getting that first whiff of aromatic steam coming off the fish is just... Wow!
The problem with the dishwasher is that it controls for time and temp, and you can't. But since most Americans seem to prefer -- or at least tolerate -- their fish radically overcooked that might not be a problem for you. If you want to try it but with control: Fill a roasting pan with very hot water. Let it come to temp in a (preheated) 325* oven for 20 minutes or so. Season, wrap, and bag your fish as you would for the dishwasher. Then put your fish in the bain-marie and cook until done.
Somehow the idea that heat from an appliance other than an officially approved stove, can actually cook things, neither surprises nor delights me anymore.
Just old and jaded,
BDL
Edited by boar_d_laze - 9/18/10 at 9:53pm