Key Points:

There's plenty of discussion on Rod Drury's blog about Vodafone's new overseas roaming call and text rates.
In short, people aren't very happy.
While I think most people would appreciate the simplification of overseas roaming by creating a handful of calling zones - Telecom did this earlier in the year, it's the pricing people don't like.
Vodafone is inviting people to join up to its Traveller plan which splits the world into four zones - Australia, the United Kingdom, North America and Asia and the rest of the world.
Incidentally, if you're in the "rest of the world", don't bother making a call, it will cost you your New Zealand standard rate plus $5 a minute. I've seen satellite phone charges almost as cheap as that!
The plan is good if you're going to Australia where you will now pay New Zealand standard call rates.
Text messages have been bumped up to 80c from 20c (though there was always an extra surcharge built into text messages sent from Australia that was accounted for separately and usually amounted to 45-50c).
It will now cost you $1 to receive calls, which is an increase in some cases. In short, by standardising its rates across the world to give people certainty while using their phone overseas, a few prices have gone up, while others have gone down.
Vodafone hasn't updated its website with the new pricing yet, but roamers have received a text asking them to dial 495 to hear about the new roaming charges.
I'm an 027 user so have to fire up a GSM phone half the time I go overseas. Last time I was in Europe I bought a T-Mobile SIM card in Germany (which required overzealous scrutiny of my passport) but gave me reasonably cheap calling and came loaded with 10 euros of credit for free.
That would be my advice when going overseas - buy a local SIM card.
Unless you're in Australia or the UK, stay off the phone. As for mobile data roaming...don't even go there. Next time I head overseas I'll be taking my iPhone and using Wi-Fi hotspots to check my email - a local SIM will look after any calling or texting I do.