Here is the conversation on Twitter:
oh look, Yahoo Pipes doesn't respect robots.txt. I am SHOCKED! (ip block ban time)
@codinghorror should RSS consumers obey robots.txt? Pipes doesn't crawl, it's directed-if you robots-off aggregator, why publish RSS at all?
r @simonw Pipes is crawling HTML when we explicitly told it not to in robots.txt. Verified logs. Result: perma-ban from all IP ranges.
To me, it sounds like Jeff doesn't understand that Yahoo! Pipes isn't a robot and therefore has no need to obey robots.txt and that Yahoo! Pipes is for more than feeds - they have specific "modules" designed to retrieve XML, JSON, and HTML (all offered by StackOverflow).
Was it really eating that many resources? I know a new server was installed for GoogleBot to have fun with, since it wanted to index gigs of stuff from SO. If it was, I can understand blocking it - it's far more important to allow your users to have a good, unhampered experience and then to allow indexers to play with your site (as far as I know, Pipes does not index anything).
I was actually playing with Yahoo! Pipes (since Google doesn't have anything like it that I know of) to try to come up with some cool SO feeds that I can make public, but also parse for cool data, so is there an explanation other than "it doesn't obey rules that I think it should"?