LOL @ 9 million - it seems that way, doesn't it? I "regular" Morton Iodized salt
unless the recipe specifies otherwise, particularly for baking. As Mar mentioned, a lot of recent cookbook authors have started specifying what they use in theirs, since it does make a difference in taste of the finished product.
I keep a crock of kosher salt next to my stove for cooking, iodized salt in the cupboard for baking, and on the table a shaker for iodized, and grinders for both sea salt and the pink Himalayan sea salt from Trader Joe's.