Depressing release day for Apple’s iPad perhaps (their stock didn’t go bazirker); however neither did it when Apple originally released the iPod — it took about 6 months to a year before the iPod became mainstream (I’m sure it will impact their stock the same way for the iPad).
I’m betting the iPad has it’s uses (and people will want it) — digital magazine, books, recipes, couch, in bed, passenger in car/train etc….when you don’t want to lug a laptop around, and want a little more screen real estate than an iPhone/iTouch, you’ll want an iPad.