I've never heard of the term before... but it's good to have a few links for this stuff:
http://it.slashdot.org/article.pl?sid=07/06/30/172218
The idea is to push random inputs into your website with an automated (logging) tool so that you can try and break your site.
Semi-related: saw a reference to Fierce - it brute forces a domain to try and find host names of interest. (tags: DNS)
Tags: security, software, automated, hack, website,