Well, this time China is hosting WCG, meaning that the old saying: "two heads are better than one; five heads are better than two; 1.4 billion heads are better than anything less than 1.4 billion", - is kicking in. So, they posted a guide on how to watch WCG 2009.
It's plain and simple, as described here.
1. You can watch it LIVE on WCG Webplayer or watch repeats about 24 hours later on Youtube.
2. All you have to do is install Octoshape. You can do that by either manually downloading and installing the thing, or simply pressing "Get Plug-in!!!" in WCG Player window, like so (click on the picture to go to WCG Webplayer):

Sounds simple enough.
Of course, if you prefer watching repeats on Youtube without any spoilers rather than live action, you might want to invest in a shovel and dig a small pit where you would have to stay for four days, unfortunately there's no guide for that, yet.
Opening ceremony will be broadcast live tomorrow, November 11th, 17:00 CST, 10:00 CET, 9:00 GMT. Here's the schedule (click to enlarge):

If you follow the Schedule link below please pay attention that there are two stages: Maing Stage and Second Stage, meaning we get much more streamed games. Stage #2, however, will probably have no commentary.
Links
WCG.com - Guide
WCG.com - Webplayer
WCG.com - Schedule