> Ultimately, IDNs are a browser / client issue, with a little bit of policy around stopping phishers et c. Down in the engine room where the registrars operate, they don't look any different to other names.
Yes there is a difference with .nz registrar's. They have to upgrade to using a newer format (see http://nzrs.net.nz/sites/default/files/idn-documentation.pdf)
If you try and register an IDN domain in most registrar's interfaces (not all) it will fail as they are not sending the extra fields in the XML for IDN's as specified in the above document.