This is from a member of the Golden Gate Tri Club. I agree that cold showers make no sense (in this context) but I found it helpful to go for some swims in 52 degree Lake Michigan to get ready for 2000 race. I'll be starting May 1st or so, the more the merrier, 6 am start times.
I was still living in HI when I did my first Escape. I got some good advise from Karlyn Pipes-Nielsen (google her if you want to see an impressive swim resume). She advised me not to try to acclimate myself to cold water with the cold showers and such (they are fairly miserable and make you dread the cold). Just jump in and go. Which I did. And it worked. Really, the cold is not that bad after the initial shock that takes your breath away. After about 2 minutes you are numb. Sometimes if it is especially cold ( <55 ) I get a headache at first, but it goes away. Whatever you do, don't forget your earplugs. It'll be fun, we'll take a dip at the AP when you guys get in, then the open water will feel great on race day (its warmer out there). If any of you want a real swimmer to escort you on a faster paced swim, I can check with my friend Aaron (he's a member of the South End Rowing Club). He took me on my first swim at the AP- he doesn't wear a wetsuit. He's also one of the swimmers featured on Pedro's Swimming form Alcatraz video.