If we're talking about "dyndns" type services anyway, why don't users get a bunch of accounts for the different entries? (in fact, most service providers would probably support a wildcard). If you don't own the domain you use for your server anyway, you might as well use something like that for conferencing or transports.
Is it possible to setup wildcard SRV records? Would you set it up like _xmpp-server._tcp.*.example.com ?
Would that work? Richard
