I love that quote, David. :)
I think that brevity is important here, and the purpose is just to tell them that their vote may not be counted, and not to take it personally. Here is the exact text I used, which I think makes the point adequately:
Welcome, {{PAGENAME}}! We noticed that you placed a vote on [[{{{1}}}]]. Participation in the community is encouraged, of course, but your status as a brand new user means that your vote ''might not'' be counted if the administrator that tallies the votes believes that you might be another user logged in under a second account (a so-called "[[Wikipedia:Sock puppet|sock puppet]]"). Please understand that this is a common practice on Wikipedia, and that it is necessary to prevent deliberate "loading" of our votes.
Of course, it's subject to change, but I really think that it should be kept short.
-ClockworkSoul
David Gerard wrote:
Don't forget to note that "Votes" for deletion aren't "votes" per se - they're an attempt to ascertain whether there is community consensus to delete. If you've made your first-ever Wikipedia edit to VFD, and were there only because of a call to arms on another site, you might reasonably be considered not (yet) part of the community in question. That would need noting.
(This is similar to the Calvinball rule of Wikipedia policy, i.e. "if you think you've come up with a stunningly clever hack of our rules which will get your way against our community wishes, good for you! The rule just changed.")
- d.