Is it recommended / allowed to answer example questions in Area 51?
I would not recommend it because there is no real purpose to this. The example questions are used to help define the scope and feel of the site. Answers aren't really useful in the define stage.
I do agree with @jzd mostly, but I think it is not so absolute as he states.
Giving this discussion a chance, and to balance a bit:
Allowing example responses could not be such a bad idea since I have seen question I though were bad or useless get excellent very helpful answers.
I think the quality of the answers is a good indicator of the quality of the answers (caveat: exceptions do exist).
Just wanted to add another point of view.