They both have media center functions; the xbox can read from a windows media center install on a computer on the network and can read from any uPnP stream on the network.
They both have exclusive titles (Little Big Planet for Sony for an example and Halo for the XBox).
PSN (the online service for the xbox) is free, however it sucks and a lot of the items you'd otherwise get included in your subscription to Xbox Live you would get nickel and dimed for on PSN.
