I called in to collect medication for one of my own cats yesterday and the vet called me through to show me the FIV positive cat. He's a really handsome cat and very friendly. The lady who found him and has been feeding him really doesn't want to have to have him put to sleep, but she can't put her own cats at risk by having him back.
To re-iterate Janine's post: anyone adopting him would need to be able to keep him away from cats who are not FIV positive, either indoors or in a secure run. He isn't currently showing any signs of a defective immune system, so he may remain healthy for many years.
If you might be able to help, please email firstname.lastname@example.org