I imagine they would read it if you have completed all required parts of their application. However, I would personally interpret a copied essay as a lack of interest and desire for the university from the applicant.
If you are simply looking to "check the box" and rely on the strength of the remainder of your application, this strategy could work. However, the essays are usually one of six major factors and copied essays would likely score pretty low.
Thanks for your reply, actually I ended up viewing Harvard's Fall 2012 common app, and it said that you should not modify your essay for different colleges, i.e., the same essay should be used for all colleges unless you are asked to modify it.
Your common app essay should be the same for all colleges. That's why it's called the "Common App Essay." Colleges don't want to hear why you wish to attend their school in the common app essay, so there is no need to modify that essay. They want to learn more about you in that essay. If they want to know why you want to attend their school specifically, they will have an essay on their supplement that calls for it. That's where you will write unique essays for each school in the supplement.