ACLU & tagged-URL emails

I recently got on an ACLU mailing list that they use to send out requests to sign on-line petitions and so on. Today, while skimming over another one of these "alerts", I noticed something amusing. The email contains several links to the ACLU site, requesting that users sign a petition opposing a recent nasty piece of legislation; for instance,

Please help broadcast our message across the nation: Sign our "This
November, I'm Voting My Values" pledge:
http://action.aclu.org/site/R?i=5dopkpJQPaNbn4A_kyuMzA..

and

To do that we must make civil liberties one of the top issues as
people head to the polls next month. Sign our "This November, I'm
Voting My Values" pledge.
http://action.aclu.org/site/R?i=ByYHnSn7ZbByadWPVPRB0X..

Note that these are from the textual version of the email; in the HTML version, the URLs are linked from the "Sign our ... pledge" text.

See anything there? That's right: each of the "sign the pledge" links goes to a different URL! Since someone had to go to the effort of making all these links go different places, I have to wonder whether an ACLU server is collecting statistics on how many paragraphs each user read before they clicked the link, and analyzing these stats to target and refine their marketing campaigns. I suppose this sort of thing is standard practice these days, but it's still a bit ... odd ... to see one of the main organizations that advocates for privacy perhaps engaging in this sort of clandestine information-gathering.

[EDIT: In case it's not clear from the above, I don't know and I'm not suggesting that anything nefarious is going on; I just thought this was a funny idea and wanted to share it with people. My brain is weird that way, but sometimes not everyone gets the joke, so I thought I'd add this postscript here to make it clear. :-) ]