Why do you need to access the live wikipedia for
this?
Using categorylinks.sql and page.sql you should be able to fetch the
same data. Probably faster.
In my research, the answer to this question is two-fold
A) Creating a local copy of wikipedia (using mediawiki and various
import tools) is quite a process, and requires a significant
investment of time and research unto itself.
B) A few months ago, I pulled 333 semi-random articles from the live
API -- of those, 329 of them have significant enough changes since
20100312 dump (which was the newest dump at the time). A new check
against the 20110115 dump has similar percentage.
Caveat -- my research is largely centered around the infobox template
usage, which is a relatively new deal, so they are generally being
updated frequently.
-- James