1. An apparatus for supporting message passing, comprising: an input that receives from a requesting source a request associated with a message; an information storage apparatus that stores a prioritized queue of entries; an associative matching apparatus coupled to said input and said storage apparatus, said associative matching apparatus configured for searching said prioritized queue of entries in parallel to determine whether any of said entries matches predetermined information in the request, wherein said associative matching apparatus is configured to identify, in parallel with said searching, one of said entries whose priority in said prioritized queue is highest among a plurality of said entries determined to match said predetermined information, and wherein said associative matching apparatus is configured to provide a data path for routing, from said prioritized queue to the requesting source, at least a portion of an entry of said prioritized queue that matches said predetermined information.