What would be the effect of announcing that every homeless person received a home paid for by the government. It would result in flood of money into every locality in which there was a homeless population. This money would go directly to businesses just like now. But the difference would be that both entities, the industry and the recipient of social largess, would benefit along with the economy instead of the way it is now with most government handouts simply benefiting corporations. (we have just seen this done with the bankers)
The food stamp program chucks back 78 billion smackers into the economy. That has to be quite a bit of change for the food sellers. You see both parties benefit as well as society because with food the people are likely to have better health etc. and the industry get cash.
Now the idea of where is this money going to come from is a stupid question when you realize money is worthless and we just use it to play with and that it is simply printed with no value behind it. So the only thing we are doing is making the machinery of society work instead of remaining in a state of dysfunction like we have now.