A full T1 can be ridiculously expensive ($250 / month or more) but does not necessarily give you faster speed than today's cable and/or DSL. The main advantage to a T1 line is that unlike DSL or cable internet, T1 "channels" cannot be shared by another. Believe there are 24 to a T1 line. Speed can never be degraded by others' usage - guaranteed connection speed (supposedly), which is why many businesses use T1 connections.
That's a crazy fast upload speed.