In addition to Swype, you've got access to the stock Android 2.1 keyboard (which some folks prefer) in addition to a Samsung one, which is further configurable as full QWERTY, XT9, or -- on the Captivate only -- a handwriting mode, though it's more trouble than it's worth.
ENGADGET: Samsung Galaxy S review shootout: Captivate for AT&T and Vibrant for T-Mobile