Should e-Books Be Copy Protected? article by David Pogue.
"the illegal copies are just advertising for you; people will download them, try them out, then go by the physical book. [...]
The results? It was true. The thing was pirated to the skies. It's all over the Web now, ridiculously easy to download without paying.
The crazy thing was, sales of the book did not fall. In fact, sales rose slightly during that year.
But none of that addresses my reader's initial complaint: what if, someday, you want to jump ship from Amazon's reader family to Barnes & Noble's? This is precisely the nightmare scenario that faced iPod owners who wanted to switch to a Zune. (O.K., there's no such person, but you get the point.)