While I'm unable to try it out (damn... just blew my cap yesterday), but it's interesting that tvnzondemand now has introduced 300k and 700k video versions (click on the respecting buttons in the player) - hopefully this means a whole lot better video on an 800px high screen... and better quality on a high res screen (maybe sticking with a smaller screen does have its advantages...)
I was looking for the Internet Debate from yesterday when I noticed the change, so it might have been there for a while (see here if you missed out on the TVNZ7 Internet Debate)
They've also changed the website code so that you can't just get a raw link to the videos (they previously just had a long string of text which had the links to the .flv's)