Honestly i'd rather people err on the side of scrapping wikipedia too much than live in fear of being disruptive and not do cool things as a result. Wikipedia is meant to be used to spread knowledge. That includes data mining projects such as the one in this blog.

(Before anyone takes this out of context - no im not saying its ok to be intentionally disruptive, or do things without exercising any care at all. Also always set a unique descriptive user-agent with an email address if you're doing anything automated on wikipedia).