I have found a question about technology choice with regards to web developent, which is two and a half years old. I have tried to give it a bump, but since it has already been answered, I guess nobody will think about adding a new updated answer. I am relatively new here so I might not be in the possition to come with drastical suggestions, but could it be a good idea to turn all questions and answers that are more than two years old into community wikis? Maybe also that the answers need to be reconfirmed? I know this is really drastical, but the reason for this is that technology advances fast, which means that we will get a lot of correct, but obsolete answeres around.
I would tend to create a new question. In that new question mention the old one (link to it) stating that it is outdated.
If in doubt you should just ask here on meta how to proceed with that specific question like you already did.
Since you have enough rep, you can leave a comment at the answer mentioning your doubts. Or add a bounty (50 rep should be bearable if the answer is important for you) and leave a comment at the question stating you'd like to know if the accepted answer is still valid or a new one should be there.
NEW ANSWER -
I think instead of flagging as pointed out in below comments, you should leave a comment on such old obsolete answers/questions, so that other people can notice and act accordingly.
OLD ANSWER -
We do have flagging system in place to flag for moderator's attention if you see some answer or question is obsolete and not valid anymore.