Why would it be more convenient to pull out an iPad vs a Macbook Pro when you're on a plane? By that logic, you'd get an even bigger screen with your macbook pro, and it's practically just as easy to pull that out. So that should have increased sales already. Not to mention with your computer you can play non-DRM movies if you have those. If anything the iPad might decrease pre-flight movie sales, because the TSA would think it's witchcraft--i mean, a bomb.
I see the iPad as more of a home-mobile device, rather than a mobile device. That is, it's a device mainly for home use which allows you to be mobile around the house with your information, instead of a device you take outside. A laptop is a device you take outside, because it can do so much more if you need it--like work stuff. If you're going out you'd want to know you have a more capable device on hand just in case.
Why would an iPad be more convenient on a plane? Well, cramped conditions make it almost impossible to use a laptop in cattle class. But no such problem for a smaller device like an iPad (or, I find, a netbook - 2x3hr batteries for my netbook meant I could spend most of my SFO-London flight hacking, writing e-mail and drafting blog posts - I do use mutt and vim: if I were using Word and Outlook, a 1024x600 netbook with a crappy little trackpad might have been a bit too restrictive for me).
If the iPad gets the ten hours it claims, it may be perfect for frequent flyers who want their own music, video and books, and a bit of e-mail reading and document perusal on the side.
I can fit my Macbook Pro in "cattle class." And I figure since a Macbook and Macbook Air is much smaller they'd be much easier to fit. For watching movies the small trackpad wouldn't really matter. But hey, the iPad would probably be more suited to watching a movie on a plane, if only slightly more. But chances are if you're traveling, you've got your laptop with you anyways.
It would have been better if they had all the fancy touch controls on a macbook air size device that could flip open 350 degrees into a tablet, and flip back into a normal laptop.
I see the iPad as more of a home-mobile device, rather than a mobile device. That is, it's a device mainly for home use which allows you to be mobile around the house with your information, instead of a device you take outside. A laptop is a device you take outside, because it can do so much more if you need it--like work stuff. If you're going out you'd want to know you have a more capable device on hand just in case.