Dude, this is the future and you're on the right track. But go big, or go home. The right solution includes all push(XMPP,SIMPLE,...)/pull(email,RSS,...) protocols supported by a personal proxy/server that makes one tunneled dynamic push connection to the mobile device.

Start with a big picture and modify it for a better personal/mobile experience:



The Kamailio SIP server ties in nicely with jabberd2 to provide a very good starting point, and they both already run on sub-$50 OpenWRT devices.