check this page.
http://www.winecon.com/paypal


I like the way that the top part of the page gives the illusion of peeling off the screen.
To recreate that I think I need to make a tapered drop shadow.

How can I do that in PhotoShop?

You just need to understand the nature of shadows to achieve the illusion of distance. It's not that hard to do, and, as always with Photoshop, there are many, many ways to achieve it.

Here's a good article on shadows and achieve realism:
http://www.digitalscrapbookplace.com...alism_vb.shtml