When we went in 2009, it was a buy 4/get 3 free deal; it worked in mid- and late-June and I believe it was good through August. We purchased the package right after Christmas, 2008. For our 2010 trip, we had a good PIN (35% off moderate rooms). We went about a week earlier than we had in 2009. I think we purchased the package in February of 2010.
Right now, we have a PIN like the one we got last year, EXCEPT that the dates are just like those on the public offers. We can't go in May or early June, nor in mid-August, which is what Disney is offering. I'm hoping there will be something for the actual summer (mid-June to mid-August), because we can't go any other time (kids in school, and both of us teach school). Looking at the link above, it looks like there is usually something offered in February for people like us, so I've got my fingers crossed. Without a discount, we really can't afford to drive all the way to Florida for a vacation