I agree completely that XP is more a measure of participation
than of Perl experience. For some time now, I've been thinking of "XP" as "PPP", which stands for "Positive Participation Points". On average, if a monk contributes positively to the site (in the eyes of other monks), his XP value increases, and if contributions are negative, it decreases.
I also offer myself up as Exhibit B: by week's end, my PerlMonks XP value will exceed that of the author of a well-known Perl book. I am totally not worthy!