I hear lots of people at the Tarrytown YMCA talk about it, and I thought about going, but I have a wedding that weekend. However, even if I didn't have the prior commitment, I don't know about the Hudson River water quality after Irene... But there are some other Hudson River swimmers around here that might know more than I do.
I did it 2 years ago and loved it.
It was my first open water swim -- I thought it was well run and fun.
The view of the Tappan Zee Bridge from the water can't be beat!
Have fun!