It has flash on the camera but I don't know about the program Flash.
The Samsung Galaxy S has not yet been seen with a flash.
There have been some claims about a flash online (and not from anyone who might be "in the know" either), but the Samsung Galaxy S review units at CTIA 2010 in March did not have a camera flash, and the Samsung spec sheet for the phone does not list one either.
That said, the Samsung press release photos for the Galaxy S do NOT include any pictures of the rear of the device, making it possible that they're considering integrating an LED flash into the final production unit.
But we need to end this rumor now: the Samsung Galaxy S does not currently have a camera flash that we are aware of, and you should not
expect to see the device ship with a flash.