If this "average user" ever needs to copy and paste the URL into another context, for example Twitter, Facebook, an email or text message, then it's always best if your URLs are short, concise, and informative.
It's usually a bad idea to include any needless technical information in your URLs like .php or .aspx or even .html simply because at some point in the future if you switch platforms you'll need to create a mountain of aliases for the old URLs which are still used. This kind of information isn't useful to the user, so whenever possible, eliminate it. Besides, it looks like amateur hour.
Which of these two URLs looks more friendly and inviting to an "average user" that doesn't know who or what you are, but might be interested in clicking?
Is it this one?
http://example.com/stories/celebrity-gossip/201302-hudson
Or this one?
http://web1.srv.example.com/cgi-bin/svengine.cgi?category=celebrity-gossip&date=201302&tagline=hudson&format=html
The longer it is, the more intimidating it will seem.