google "boundary training". it's pretty intense work to make it successful and i seriously doubt this owner is willing to put the time and effort into it.

are there leash laws where you live?

I think training the neighbour will yield more positive long-term effects than attempting to train the dog. Here, Animal Control would have long since levied increasing fines for failing to control her doggie.

My dogs are boundary trained. It depends on a lot of different factors for success. For example, some dogs just can't help following their noses off the property.

http://www.youtube.com/watch?v=OuTh47i3hOY
http://www.youtube.com/watch?v=oNE_WJ1nMu4

My own method is basically having well known boundaries erects so there's a clear line to not cross. You can use little red flags, a line of bushes, whatever. Then working on a dynamite recall. Every time the dog ventures near the line, I recall them back and praise like crazy. I also walk the line with them and reinforce them for not crossing over. Then you proof by having people and dogs and whatnot to tempt your dog in the distance by walking by and you reinforce the dog for not crossing the line.

All this teaches the dog the line they shouldn't cross. Any time the dog is taken over the line, it should only be when you release them to do so, WITH you. You can have them sit and stay at the line and engage your release cue word for them to know it's okay to step over with you.

Perfect, Ms. M. Thank you.

Nice neighbors don't let/allow/encourage their dogs to poop on someone elses's yard.

Watch where the dog goes, and if it wanders onto more yards than one, check out the animal control possibilities in your area. Find out if there is such a public service in your area, and if you can call without identifying yourself.

You could collect the poop the dog leaves it in your yard, and deposit it on their sidewalk, or take it to the front door.

But be advised that problems can increase from any action you take, period. One guy I knew hated dogs pooping on his lot, and he related one incident. He said once outside he admonished a dog walker to collect the poop just deposited, and guy ignored him, so he picked up the poop and flung it at the guilty party.

Not a very nice thing to do obviously, but it was a simple way to convey that the guy felt strongly on the subject.

In my area local ordinances require that stranger dog poop be picked up by the dog owner.

I couldn't care less about the dog poop. That's not the issue as far as I'm concerned. I'm concerned about the welfare of the dog.
I don't, of course, think it's right for people not to pick up after their dog. They give the rest of us responsible dog owners and dogs in general a bad name.
In fact, I can't enjoy the many nice parks in my city - that MY tax dollars go to maintain - bc dogs aren't allowed in parks.