Soon I'll be resuming work on a privacy-conscious push server design, originally intended to enhance the poor user experience of the existing ChatSecure iOS client (OTR/XMPP/Tor).

The general idea is that you'd fetch tokens from the server that allow people to send pushes to you, then distribute them to trusted contacts over an secure channel. Contacts would then be able to send you pushes from any endpoint of choice. Somewhat less metadata than existing solutions, and an opportunity for client diversity.