Yahoo! has apparently come to the conclusion that since so few uses Boolean anyway, they may as well not support it. That is a mistake. Power-users like librarians, journalists and researchers use them, and they are exactly the kind of people that influences the public opinion in these matters.
M. Collins. GECCO 2005: Proceedings of the 2005 conference on
Genetic and evolutionary computation, 2, page 1613--1618. Washington DC, USA, ACM Press, (25-29 June 2005)