I'm gonna have to say it won't support more than one gamepad but there will probably be a 5 player split screen mode or two player co-op using the gamepad for one player and the other the TV

Hmmm, not a bad idea but I don't think that Pikmin will be the game that showcases the dual Gamepad play. I think Nintendo will show that game at E3 and release it this fall as a bundle with the controller (ala Wii Fit/balance board), hopefully for no more than $99.

I don't expect any game to use 2 GamePad controllers until you can buy the thing for a max of $70.

Would make sense. I can totally see it happening. We know very little about the game. Nintendo hasn't even officially acknowledged the pink flying Pikmin species yet have they?

No... just no.

First off, this game wasn't even utilizing the gamepad at all. It works just fine with Wiimote/nunchuk.
They could have delayed it for gamepad support especially if they make it a 2-3 player game. Makes sense.

But for a launch of 2 gamepad support? No. Pikmin's audience is simply too limited and it'd play well enough with wiimote on split-screen that very very few would bother spending an extra $100 for a second gamepad that might get used if a friend comes over and prefers it over wiimote.