No, I don't think this is okay. I've seen people just go and add the homework tag to someone else's question just because they think it "seems" like a homework question. I think that's quite unacceptable.
It's extremely difficult to accurately judge whether something is a homework question, or if it's actually something that someone is working on for [what is the opposite of homework? work? what if it's a project for fun? see the problems with this tag already?].
It can be a little bit offensive to people to tell them that a problem they're actually having and need to come up with a solution for "sounds like homework". Maybe, but just maybe that's because homework sometimes reflects real-world situations that people will actually need to be able to solve. (Yes, a lot of times it doesn't. I take issue with those types of assignments. But that's quite besides the point here.)
Not to mention, I still think this a meta tag, and one that's not particularly useful in categorizing content. If someone wants homework-style answers, they should include a sentence in the body of the question along the lines:
This is a homework assignment, so I'm looking for hints, not complete solutions.
Otherwise, who are we to care and police whether students want to cheat on their homework? Why is it acceptable to give a completely written solution to a professional database administrator expected to know how to write SQL (and in a situation where bosses probably think the DBA wrote the code), but not acceptable to give that same solution to a student?
It's the student's own responsibility to act in accordance with standards of academic integrity, and the responsibility of that student's academic institution to verify that they do so and hold them accountable if they're not. It's certainly not our responsibility to do that as their fellow users on Stack Overflow.
It's quite possible for a conscientious student to receive the complete solution to a question, and still take the time to figure out why that is the correct answer and learn something from the assignment. That's really the point of homework anyway, isn't it? And it's just as possible for a dishonest student to copy the [incorrect] answers from elsewhere on the Internet. SO isn't the first or the last Q&A site to exist, and we're certainly not the only place that students can come to cheat on their homework. Let's hope we're setting ourselves apart as the place people come to get good, accurate, and useful help, not where we think it's our job or duty to decide how students should approach their own homework assignments.