Everything Becomes Lisp

"Find out how closures and lambda functions make programming easier by
letting you define throwaway functions that can be used in different
contexts. This article details how useful closures are as a functional
programming construct within PHP V5.3 code."

http://www.ibm.com/developerworks/opensource/library/os-php-5.3new2/index.html?ca=drs-tp5008