I just answered two questions back to back, both by new users. They both accepted my answer, but neither upvoted it. I see this happen fairly frequently to users (not just me), so my question is: can users upvote answers given to their question? If they can't, shouldn't they be able to? If they can, is a notice shown to them when accepting an answer along the lines of "also upvote this if you found it helpful"?
I don't believe new users (with Rep less than 15) are able to vote on any posts, even answers to their own questions. I've had the same thing you described (acceptance with no upvote) happen to me a few times, and I believe most of those were users with 1 Rep.
It would make sense for new users to be able to vote on answers to their own questions, since they can already comment on them.
I think new users should definitely be able to upvote answers on their questions. When I was new, I asked two questions. They didn't get upvoted even though I feel like they were very good and well-presented questions, so I hadn't gained enough rep to upvote, but I really wanted to let the people know that I appreciated their answers.
Accepting a 0 upvote question just felt wrong. Please add the exception to allow new users to upvote on their questions.
From the SO FAQ:
Amass enough reputation points and Stack Overflow will allow you to go beyond simply asking and answering questions: 15 Vote up
I think I'd leave the behavior the way it is rather than creating a special case where you can upvote answers to your own questions. I like the fact that you need to contribute something (a good question or a good answer) before you get voting rights. Allowing comments to answers on your questions makes sense as you may need to provide feedback to issues raised in the answer.