HigherOrderMessaging, or HOM is the application of higher order techniques such as higher order functions to message-oriented languages.
A higher order messages takes another message as its argument, just like a higher order function takes another function as its argument.
A paper can be found here: http://portal.acm.org/citation.cfm?doid=1146841.1146844 Alternative location for those without ACM access: http://www.metaobject.com/papers/Higher_Order_Messaging_OOPSLA_2005.pdf
-- MarcelWeiher