"a testiment to the organisational power of social networking sites like Facebook"
I think that might be going a bit far. What it is testament to is that we're all fed up of shitty pop.
Previously, we've all been too fragmented, "I don't like shitty pop, but I do like cool jazz" (etc.) so (as with many democratic systems) the thing that the largest people like (which also happens to be the thing the largest number of people also dislike) ends up getting branded "good".
What happened here was that, pretty much by accident, someone found something that everyone sort-of likes (Killing in the name of) and were able to use as a banner behind which to mass to express how much we dislike bloody x-factor. I, myself, have been not buying X-factor records for many years and have had absolutely zero effect on anything, This year I bought two copies of Killing in the name of (I song I like) (and the second one was a mistake, bloody iTunes) and now can delude myself into thinking I might have had some small influence on Simon Cowell.
Next time he's putting together an identikit pop star perhaps he'll pause for a moment and think "Should I make this one staggeringly hopelessly bland? No, I'll raise my game and just make it very bland". Which is, at least, a step in the right direction.
And (back to the point I started with), they tried this game last year, but chose Rick Astley. And even with the "organisational power of social networking sites like Facebook", they failed.
I think Facebook was probably fairly low down the list of causes for this. I think the real things that helped here are:
1) Wide spread public anger
2) Choosing the right song
3) The BBC (where I heard about it)