An updated internet-draft is available from the IETF.
Abstract: «Push Extensions to the IMAP protocol (P-IMAP) defines extensions to the IMAPv4 Rev1 protocol [RFC3501] for optimization in a mobile setting, aimed at delivering extended functionality for mobile devices with limited resources. The first enhancement of P-IMAP is extended support to push crucial changes actively to a client, rather then requiring the client to initiate contact to ask for state changes. In addition, P-IMAP contains extensions for email filter management, message delivery, and maintaining up-to-date personal information. Bindings to specific transport are explicitly defined. Eventually P-IMAP aims at being neutral to the network transport neutrality.»