My thought on this is that could more harm than good.. One it adds even more reasons that motivate some the of silly things like XP whoring and bots etc. Second even if XP had anything to do with skill level, it would still be general type of rating. The fact is I might have tons of rela life experience in using Perl for sysadmin type (polling machines, reading logs etc) and know next to nothing about your CGI question or vice versa.
Usually the way i approach something is to read all of the replies to a node that has been around for at least a day or so. If any of the responces are 'mistaken' or this is a better approach there is almost always a followup comment on it. This gives me a real clear idea of what is a good approach as well as telling me wy it is a good approach. Anyway the last thing we need it is to give people a yet another reason to get filpped out over XP.
Edd