Apparently, by not unblocking scripts for "ajax.googleapis.com", I am unable to vote on LW. I generally dislike enabling scripting for domains that are used in many places -- unblocking Google APIs would unblock it everywhere, not just here -- so the result is that I am no longer voting. I suspect that I am not alone in this.
(Apparently I can't post without enabling it either. Looks like I'll have make an exception and do the script-on-script-off dance after all. Whee.)
LW uses that domain to serve jQuery and Prototype. This is a recommended practice. The voting and posting code both rely on these libraries.
It sounds like what we want is failover: "if the user can't get jQuery from Google, then give it to them from LessWrong." Here is how to do it.
CDN failover is a best practice in general because it keeps the site working if Google ever goes down.
If you use Firefox, you may be interested in this.
This seems to work quite well, thank you!