It's true, once upon a time my job title really was "Usability Tsar". And I have the business cards to prove it.
Update, 2005 : WTF? I cannot believe that this discussion is still going on!!! : http://www.veen.com/jeff/archives/000705.html
I gave up thinking and writing about this kind of thing because I assumed everyone got it. (And because I spend all my web-time on internet literate (typically amateur) sites like weblogs and wikis, and at clueful companies like Google and Flickr.)