Well, I suppose he wants to leave his team after China (or Brazil, wherever the last race of this season is). But I kinda understand him. Even if McLaren isn't blatantly supporting Hamilton, the crew -still- are most british, and that's making him feel like the 2nd driver. Kinda like "We love you Alonso, you're the world champion... now help us make another champion out of Hamilton. Give him the car we developed along with you during the pre-season, and your car setups too" (Like it or not, Hamilton doesn't have half the experience to setup an F1 car properly, and his car would be half a second behind Alonso if McLaren didn't allow sharing setups between drivers). That's probably pissing the hell out of him, seeing the results of the last two races, which are making Hamilton look like a semi-god while the merit isn't 100% his. And nobody thinks about that.
Give Hamilton the '03 Renault car, with Trulli as his teammate, and see if he can manage to win a race like Alonso did in Hungary, all by himself. And THEN develop a winning car to fight a real god like Schumacher. I'm not saying he wouldn't (in fact, I DO think he would, even winning earlier than Alonso did), but he's having it way TOO easy to win, with an (by now) unmotivated teammate, the fastest car by far and a double champion's setup.
PD: I'd love to see what Vettel would do in Hamilton's place, too.