Minor point-- if you want links to look nice in articles, you need to use html rather than the markdown which is what works in comments. I don't know whether putting up with this is a sign that we're unusually intelligent.
Ahh. For some reason, I was convinced that the link worked before I edited my post, during the process of which I didn't touch the link. So I just left it there, out of frustration, it was clickable anyway. Fixed.
Maybe HTML does suggest something about LW's IQ, but it is not really useful, given the current evidence we have so far. The way I interpret it, it says that the average IQ is probably over 110-120 (no upper limit), with a quite weak reliability. Even if we don't take into account that 20-70% of the users know programming (many people don't study computer science, but still use programming).
The latest survey shows that the average LessWronger who entered his SAT or ACT is roughly in the top 0.11%. This is insanely high. For comparison, top 2% can be Mensa members. I do not know the correlation between SAT/ACT and IQ, but I know it's fairly high. Anyway, I'm very curious to see the average score on a real, culture-fair IQ test. Those are the only two tests that are free, online, correct and culture fair, from what I know.
http://www.cerebrals.org/wp/tests/jcti/
http://www.etienne.se/cfnse/
Many people would prefer not to have people knowing their scores. That's great, but please please please do post it anonymously. Especially if it's a low one, but not if it's low because you rushed the test.
JCTI might take a while, so I recommend keeping your answers on Notepad in case you want to leave it and continue later.
Edit: I have included polls, thanks to the commenters.
Post your score here: http://lesswrong.com/r/discussion/lw/fqq/average_iq_on_lw/7yad/