Seems a shame that Wikipedia (rightly) doesn't allow original research. This is very interesting reading. :-)
I seem to remember that Wikipedia had it's millionth edit (or something like that) not long ago. 10-20% might not seem much, but it helps put it in perspective.
600,000 articles would be the latest milestone for the english wikipedia.
This shouldn't be a a problem, however. The system must be storing the last IP used by a user, since this autoblock-on-access mechanism cannot operate without that data, so it can easily be checked at the time of an admin setting a block.
It's storeing more than the last. It is not uncommon to see strings of auto blocks appearing