Just thought I'd share, the following waterproof cases are available for the Pocketbook 360. There's nothing like reading a book while floating on a lazy river!
http://www.thewaterproofstore.com/aloksak6x6.html
I have this one, and it works great, but it tends to get "creases" in it. The Pocketbook fits in it perfectly, I put the "zipper" on the other side of the buttons, and just fold it over to the back.
http://www.thewaterproofstore.com/drypakpda.html
I just ordered this one, it should fit perfectly based on the dimensions shown. It's a new product, and it's currently on sale for $16.95. I have the wallet case by the same manufacturer, and based on that, this should work well for reading through it -- it's a softer plastic than the bag above, so it doesn't get the creases.
I'll report back once I get the second one to let you know how it works!