using wireless gateway as a radio emisor

I'm too lazy to read all the responses, but [link=http://ask.slashdot.org/article.pl?sid=04/12/26/0221231&tid=222&tid=186&tid=4]This article[/link] on slashdot is similar to your question. Perhaps you can find something there.

Hmmm... well no... that program is an excelent tool for streaming mp3's radio signals, but I was thinking more in the lines of a standard radio signal

I thought wireless modems run at a much higher frequency (~2.4Ghz probably) than your standard radio station (87Mhz-108Mhz). But it'd be cool if you could modify it to broadcast at custom frequencies....I'd like to know about this as well

You would probably have to make/find firmware to get it done, though I highly doubt that you will be able to get the device to broadcast at a standard radio frequenc, ntm getting it to broadcast an actual fm signal. And (assuming you live in the US) the FCC may not be to happy about your home station, all broadcasters in those bands need to be registered with them (the exception is a personal fm transmitter, like the ones used to transmit a signal from a cd player to a car radio).