As a town that is completely dependent on higher education, it should go almost without saying that the apartment market is also completely depending on the post-secondary institutes within town. When the MIT and Harvard graduates start leaving Cambridge in May and June of each year, that is the time to swoop in and start picking over their apartments.
Most landlords in Cambridge will expect you to have some sort of ties to one of the schools within town. Because the schools are so important, supervisors or professors make excellent references on rental applications. If you're not a student, an employment reference will be important for securing an apartment.
Public transit in Cambridge is excellent. The subway system connects not only the major destinations in Cambridge, but also connects the suburb up with the rest of the Boston Area. The Massachusetts Bay Transit Authority runs until just after midnight. Bike lanes are common as well, and many people cycle to commute to their schools.
Museums abound at Cambridge, with some excellent ones at both MIT and Harvard. The MIT Museum features great modern science displays, and the Harvard Museum of Natural History includes a collection of dinosaurs. If you enjoy theatre, the American Repertory Theatre is one of the best outside of New York or Chicago. The Muddy Charles Pub is a hangout for MIT Students, while the Ha'Penny or Club Casablanca are good places to find Harvard attendees.