He was happily living with several other dogs in his foster home, so it took us a while to realize that his dog-dog skills are quite as bad as they are. Initially he was easily and strongly distracted by quite a variety of things. As our training progressed, he got better at ignoring the other things, but the only improvement we saw with dogs was that he got faster at recovering after freaking out. We got a little extra private help from our trainers, and learned some refinements to our technique and some more detail about the psychological principles at work. This has been really helpful, and we're getting detectable results, but we've got a long way to go until he can walk calmly past another dog or say hello politely.
The procedure basically consists of two parts: First, get him to associate seeing another dog with a positive, relaxed experience by giving lots of treats every time he sees a dog. Then, once he's got that association really firmly established, he won't slip into freaking-out mode and will be able to listen to us telling him what he should actually be doing. So whenever we're out on a walk, I keep a careful eye out for other dogs so we can stay just outside of freak-out range and have a positive experience.
The folks who live in a particular house we often walk past sometimes leave their screen door shut with the regular door open. Their small dog likes to sit there and watch the world go by; if the world includes Galen he's likely to start barking at us, which stresses Galen out. Yesterday afternoon, I saw that the screen door was shut and Galen saw something interesting in that direction, so I got all prepared -- shortened the leash a bit, readied my clicker, watched the door to see if the dog was there or behind the house instead -- and only then noticed that what Galen had actually spotted was the cat that also lives there, who was standing just on the other side of the fence. Galen and the cat happily and enthusiastically sniffed noses. I tried to reward him for this nice polite interspecies behavior, but he was all "Mo-ther! I do not want a treat right now! Can't you see I'm talking to this cat?!" (I don't ordinarily feel I have a particularly parental relationship with this dog, but damn does he do a good teenager impression sometimes.)
This same cat has sat at the bus stop next door, getting pets from some guy, while Galen walked by mere feet away, barking and carrying on trying to get over to see the cat. I've never been sure whether his interest in cats is more like his interest in other dogs or his interest in squirrels, so I'm very cautious about letting him interact with them. But Fearless Cat seems quite confident that Galen's after a social interaction, so I'll take that as a good sign.
 All our classes and things have been through A Dog's Life. We like them.