Public Service Announcement:

Windows Phone 7.8 is now available via Zune. If it's not showing there's an apparently risk free technique to force it onto the phone (I've just done the first update via this method, no problemo, and the second one is in process now - I'll let you guys know how it goes).

Details: http://www.wpcentral.com/forcing-windows-phone-78-update-camera-button-not-required-patience