Today’s UseIt newsletter by Jakob Nielsen puts the usability of search engines among the leading factors of web usability:

“Search engines are the archetypical embodiment of the mastery ideology. They place users firmly in the driver’s seat and take them where they want to go. You can get anywhere on the Web using a subservient interface that accepts any words you throw at it and serves up a simple, linear list of rank-ordered choices.

Not coincidentally, ever since the WebCrawler debut in 1994, users have proclaimed search as one of their main activities on the Web. Being in control feels good…”

Nielsen further lists search engine advertising among the champions of web empowerment, by stating that “most successful Web ads empower — rather than annoy — users.”