Three guitarists. Lots of pedals.
Whilst it's pretty hard to do well, I do think there's an element of "anyone can do that" which explains why myspace is full of mediocre "post-rock" bands who've heard one Mogwai album and decided they can do it.
It's actually quite easy to get away with not being very talented as long as you can go really quiet then press down on a pedal and go really loud, and then go quiet again. It'll sound really erm..."ethereal" or something.
For a listen or two it might actually sound ok.
"Post-Libertines Gash-Rock" (that's actually a genre, there's a whole department in HMV)
Requirements: Hat. Waistcoat. Skinny trousers. Pretend drug-habit. The occasional piece of faux "Social Commentary" about a bin man who reads Bukowski. Oh, and when you go on Popworld, remember to handily leave a copy of "Crash" or "Fear and Loathing" sticking out of your pocket so it gets brought up in the conversation.
Lyrical content: Over romantisied songs about wherever you live (inevitably North London, though New Cross is also acceptable) Songs named after girls who didn't shag you, or did, but then realised you were a cunt and caught the next bus out of Hoxton. If there's a girl named after a place who didn't shag you, you are pretty much guaranteed at least a Babyshambles support slot.
You can get away with not being able to write songs as long as you release a single with a sing-along chorus (it doesn't actually have to be catchy, as long as you get five people shouting it in the background on record so you remind people who hear it that it's your sing-along catchy number) and a riff knicked straight from the Ramones or someone and play the Rhythm Factory lots.