This WAS working but somehow I've messed something up. I've also followed the advice here: http://www.gravityhelp.com/documentation/page/Testing_for_a_Theme/Plugin_Conflict
My form looks great, but it's not sending emails, it's not redirecting to a confirmation page (tried text, page and redirect).
It's also doing something strange with the contact form page AFTER hitting submit. Probably easier to just take a look at the test page: http://www.weddingdj.co.nz/gravity-test/ (identical copy of what I was trying to make happen live - this page is currently hidden).
The result looks very different in Chrome vs IE vs Firefox.
I'm using the very latest update, but the problem existed before 1.6.9. I've tested this with the Twenty Ten theme, I've deactivated all plugins. The only active plugin is WP-Hive which I can't deactivate without destroying the site. Gravity and WPHive worked fine together before, and neither had any updates.
It WAS working, and in the past I'd used a custom PHP mail plugin, but I managed to get this working without it sending through my Gmail SMTP server.
I'm confident I've inadvertently created some sort of conflict, somehow. Please help!
Nick in New Zealand