How are the dorms assigned freshman year at an university?

The process varies widely depending on the school. Some schools do send out surveys with questions like, "Do you prefer to sleep with the window open or closed?" You know, stuff that could cause friction between new roommates. Others do the process more or less randomly. The residence life staff at the school will likely be more than willing to share with you how roommate assignments are made if you ask.

It completely depends on the school.

The school I'm at had two options. If you knew the name of someone you wanted to room with, you could both sign the form and they'd put you together. Otherwise there was this huge 500 question survey about your lifestyle (like seqdhea said) that had things like "Do you smoke? What time would you prefer to go to bed? Do you think you will spend a lot of time in the room? " and some personality things "Are you generally organized?" etc. They claim to have a computer matching engine or that picks the best matches, however at my school, I'm pretty sure that "computer matching engine" is code for "a group of 10 people".

Best thing you can do is just contact the school(s) you're curious about. Or go to their websites and try to find stuff about "resident life".

At my school for some reason they seemed to group people by name... in my dorm there were a pair of Matts and 2 sets of Bens.

@Perchik: "I'm pretty sure that 'computer matching engine' is code for 'a group of 10 people'." LOL

@andrew: yes, I worked at a couple of schools where "a group of 10 people" did the roommate matching. All kinds of crazy antics ensued, like matching people with the same birthday, same first name, etc. Anything to help alleviate the boredom of going through thousands of housing requests....

in rutgers, they make you take a survey but eventually most people get dorms with the people from the same ethnicity