[Dovecot] Sieve extension registration

Cool, I just happened to notice this while browsing...

From <http://www.iana.org/assignments/sieve-extensions>:

 Capability name: vnd.dovecot.* (anything starting with "vnd.dovecot.")
 Description:     Extends the Sieve language with vendor-defined
                  functionality specific to the Dovecot Secure IMAP
                  server (http://www.dovecot.org).
 RFC number:      Not applicable
 Contact address: Stephan Bosch <stephan&rename-it.nl>
                  Timo Sirainen <tss&iki.fi>
 Registration Date: 2008-07-28

Any current plans for it or is it just a placeholder?