Talk to your lender, the credit will not work for a downpayment.

I'm pretty sure that part made it in ... obviously you'll have to close before the 2008 tax filing deadline to include it in your 2008 taxes.

Here's a point most people have not mentioned and it's pretty important. The tax credit is yours to keep as long as you keep the house for 36-months. The actual wording the filing form (5405) says is:
"You must repay the credit only if the home ceases to be your main home within the 36-month period beginning on the purchase date. This includes situations where you sell the home, you convert it to business or rental property, or the home is destroyed, condemned, or disposed of under threat of condemnation. " (page 2 of IRS Form 5405)

I'm not certain if this made it into the final bill, but at one point you could claim the credit on your 2008 taxes if you bought early enough in 2009.

Thumbs up,Lara for a realy good answer.(the first one--not the second!)

Oops I forgot the second link...

James,
There may be some confusion to the 8000.00 stimulus benefit for first time home buyers. Home buyers who purchase a home from the start of 2009 through Nov. 2009 may be eligible for the lower of an 8000.00 or 10% of the value of the home, tax credit...remember that a tax credit is very different from a tax deduction which only reduces your taxable income.
You really technically would not be using the house stimulus benefit as a down payment as you will be waiting until the new tax year in January 2010 to get that 8000.00 in the form of a credit. It is not upfront money. The credit is applicable to any home that will be used as a principal residence. Qualifying homes include single family residence, condos, townhouses, maufactured homes, and even houseboats that qualify as a principal residence. I would suggest you look at the details at the goverment website indicated below. Let me know if you have further questions or need further clarification. It is still good practice to consider saving at least 3% as a down payment and if you have any concerns or just want to know your cost on out of pocket expenses. Talk with a qualified lender...they are really fully aware of all the ins and outs right now. Just like us Realtors...it's important for us to be able to guide and know the facts about the market.
Best of Luck,
Lara

No. The money is not available at the time of purchase. That's part of what I like about the tax credit. It replenishes peoples' bank accounts rather than giving them the money necessary to buy.