We were discussing on wikitech-l a month ago why we see so many hits to the edit page which don't result in a save attempt. My theory was that the majority of edit requests were due to readers clicking red links, not understanding what a red link indicates.
http://mail.wikipedia.org/pipermail/wikitech-l/2005-November/032239.html
A comparison of edit page requests and their success rate before and after the recent page creation policy change yields some interesting differences. The following figures are based on profiling data gathered on November 8 and December 8. They are both gathered over about 24 hours, and so do not take weekly fluctuation into account.
Before the policy change, 97.1% of edit page requests passed the authentication checks. After the change, only 65.5% did. This means that the "page creation limited" error page is getting roughly 3.5 hits per second.
So it's hardly surprising that we've seen a jump in account creations, because we're now advertising account creation on one of the most heavily visited pages on Wikipedia, the "page creation limited" error page. We're tapping into that constant stream of confused readers clicking red links.
-- Tim Starling