How many game developers have pledged this game?

All I know are notch (the developer of minecraft) and googlefrog (the developer of Zero-K), but maybe there are more, like some guys from GPG, Relic or even Blizzard. Ron Gilbert and Clayton Kauzlaric are likely too, they're connected to Cavedog anyway.
Have anybody found any game developer's name or nickname in that long backers list?

Depends how famous you want them to be.
I work for a games development studio but have backed this game as TA/SCFA took away 15 years of my life.

I have developed a few games just for fun myself, does that count? xD

I dev the Spring engine.

Backing PA WHICH IS GOING TO STEAL ALL (5) OF OUR PLAYERS AWAY probably wasn't the smartest move I ever made.

hehe.
you guys should fix the zoom of spring so it works as good as in supcom and I might try out spring again

James Green, one of the guys who made AirMech, said he'd pledged on the stream.

I am not a working gamedev YET . I should be done with school somewhere around the release date of PA and then look for a job.

I backed it.

In Brainfuck?

actually I guess very very many developer backed this game. non-famous and famous ones. I guess he just wanted to know which famous ones backed.

In java.
A 2d jump and run with physics-simulation and a mapping and scripting system that is flexible enough to support maps that implement tetris or pacman. Got a perfect score for it in my final school-graduation.

Once someone sent me an e-mail praising me for a map I made for TA. Does that count?

well even you are not trolling, you would be counted as map creator/editing

Well some of the Bungie guys probably backed it, as they showed up at the countdown party which meant they knew about it.

I was jokingly referring to your signature...

I pledged $120 to PA and i help with development of Zen Pathz by Limn Interactive.

I have made some flash games for fun, technically got payed for helping someones from a flash forum code there game, despite telling him I'd do it for free. dose that make me a professional coder?

And I was just bragging around about my oh so nice little project

I backed it, by reverse logic, does that make me a famous game developer?