The International, Valve's $1,000,000 Dota 2 tournament , has begun! You can watch it live on the Dota 2 website . Right now IG are playing EHOME in the opening match of the tournament.
Interestingly the stream page includes character descriptions for the different heroes currently in play. There are ten on show right now; Sven, Clockwerk, Tiny, Tidehunter, Pugna, Weaver, Ancient Apparition, Spectre, Lich and Lion. Check the tournament page for more details.