jargon.artrocity.com
New Hacker's Dictionary the Jargon File v 4.4.6
[prob.: from ad-agency tradetalk, ‘house freak’] A hacker occupying a technical-specialist, R&D, or systems position at a commercial shop. A really effective house wizard can have influence out of all proportion to his/her ostensible rank and still not have to wear a suit. Used esp. of Unix wizards. The term house guru is equivalent.