Correct me if I'm wrong, but immediate expensing of capital equipment just means that tax reduction through depreciation of the equipment is moved up to the current year. So if you spend $5,000,000 on a machine with a 5 year depreciation schedule you could deduct $1,000,000 per year as a business expense. If you were going to buy the machine anyways, that means with the immediate deduction you have $4,000,000 lower net income this year, but $1,000,000 more than you would have for each of the next four years. Net change = $0. Money now is better than money later, but it's still just shuffling when the deduction happens.
How is this different from Cash for Clunkers and the housing tax credit since it would just shifting future purchases to the present and reducing future purchases?
Well, it also allows 100% deduction on labor, which is usually a large portion of capital investments. Normally, when you take a $5 million deduction (a deduction off your gross), you only get 36% (or whatever your tax rate is) off your taxes.
I think that this is different as it allows you to take ALL of the capital costs off your taxes.