It's actually not very much mograph at all.  SXSW is split into 3 conferences.  Music/Film/Interactive

Music/Film are pretty self explanatory.  The interactive conference kind of shifts focus every year, but for the most part, the last few years it has leaned HEAVILY into the design and marketing of social media/social apps.  But that's not to say that is all there is to it.  A lot of what's of interest is the conversations that take place in and around the sessions.  There's definitely a strong hype quotient but also a lot of really fascinating thoughtful designer/engineers floating around…  You're guaranteed to leave with some interesting new info