i think you get a minimum of $300 up to a maximum of $600. i don't know how they determine it. although -- and this is a rumor i heard, and not something i've investigated myself -- you may have to pay your stimulus payment back to the IRS when you file your 2008 tax return.
Paying it back is something that happened when we got the last $300 Loan from the gubment. They played like it was free money and many people blew it of frivolous shit, only to find out that it was an interest free loan that had to be paid back. I was doing taxes at the time and loved watching conflicted Bush lovers curse him for making them own the IRS because of the loan.
I have not heard if it is a rebate or advance. I thought rebate, but always, always expect that this gubment will find a way to take that money out of your hand and put it in the hands of people that really, really do not need any more money.
I'm halfway through a book titled Free Lunch by David Cay Johnston. It's on the fascinating subject of government subsidies. Sounds dull, I know, but you would be amazed (and probably enraged) if you knew how much money and property is taken from average (meaning poor to middle-class) american citizens and funneled directly into the pockets of the uber-wealthy. When I'm reading it I find myself grinding my teeth.