The statements that the government doesn't care about homeless veterans and doesn't acknowledge the existance are, in the words of the vernacular, a bunch of shit.

The Federal government, through the VA, has an active program of funding homeless programs, and the link to information on that is here. In addition, the agency manages a network of Domiciliaries for homeless veterans and funds State Veterans Homes as well. Many veterans on the street will not go to these places because they have a zero-tolerance for alcohol and drugs policy. There have been studies done that imply that many of the "veterans" on the street have no military service, but have learned to claim this as a way to elicit extra benefits. One study summary I do have says that 1/3 of homeless men in the 1980s were veterans...of all wars. It also states that, at that time, about 40% of adult males were veterans (Stolen Valor, B.G.Burkett, p. 317), which would indicate that homeless veterans were perportionate to the overall population.

The VA also has a very active medical research program on Gulf War issues. dedicating to studying the multiple issues that have been lumped into the term "Gulf War Syndrome" by the uninformed. The January 2002 report to Congress on this program is here.