I had a big surprise at checkin at my hotel (Disney Ambassador) when the cm asked me which kind of four-day pass I wanted. Huh? It turns out that they are now offering a four day pass which allows parkhopping on the first, second, third, and fourth days--in other words, on all four days. The normal 4 day pass costs 15,000 yen and this added 6,600 to it.
There are variations with 2 and 3 day passports which also allow parkhopping on all days, but can't remember the prices.