Suppose I asked a Rails question 3 years ago and got a good answer for Rails 2. Since then, Rails 3 has a different way to solve the problem, so someone posts an answer more suited to Rails 3. The Rails 2 answer is at the top because of its longer history. (This is a very common occurrence, BTW.)
Some think that a comment linking to the other answer is all that is appropriate. However, I think the top of both answers should include a line that says "This is for Rails 2. Please see the answer from xxxx for Rails 3" and vice-versa.
Is appropriate to edit an answer just to mention framework/language/OS version as I mention above?