Why not use use some kind of push oriented or streaming protocol such as XMPP or the Six Apart Update Stream?
SUP has been designed to make life as easy as possible for feed publishers. Since it is based on simple HTTP and requires no special libraries, it can easily and efficiently be implemented in almost any environment or language. For example, Laconica/Identica implemented SUP in about 45 lines of PHP code (plus 2 lines to add the necessary HTTP header). SUP does not require streaming HTTP libraries or long lived HTTP connections (which are difficult with many hosting environments), and it does not send a lot of unnecessary data (since it includes only a minimal ID instead of the full Atom content). Once feed publishers make this information available via SUP, then other people can build additional services that translate updates into HTTP callbacks, XMPP, email, or any other protocol desired by feed consumers. However, if feed publishers do not share this information at all, then none of these other services would be possible. Therefore, SUP is designed primarily around the needs of feed
