Rickochet I hear you on that, but I look at it as something similar to the baskets of condoms around college campus'. You can't stop them, but you might be able to at least stop the spread of disease. Is it perfect? Absolutely not. Better than more cases of AIDS, Hep etc? Yes.
I could go into a long over thought speech about my feelings on trying to fix/help/save everyone from everything, but that gets out of hand quickly. Offering help and helping save those who do make it out the other side is the important part of the addiction world, so as bad as giving them needles may be, it's better than the alternative death sentence.