West Ham vs Arsenal - Live
LiveFooty have a number of streams for today's game. SopCast, TVUPlayer, JustinTV (although last week the EPL seemed to manage to get the West Ham streams closed on JustinTV), UStream (last week's UStream stream of West Ham's game was very good quality).
FSICrew also have links to lots of streams.
If you are in the UK you can also watch today's game live on Sky Sports 1. BBC 5 Live have second half commentary of the game. Radio London think a London derby between West Ham and Arsenal will be of no interest to Londoners. Instead they are concentrating on the bore fest fringe interest sport of NFL - what this has to do with London is anybody's guess).