I know the stories of 'my friends uncle's dog works for xyz' surface at times like this, but my friend is a manager in an Orange retail store and has informed me of the tariffs for the iPhone 4 which were posted on the company intranet last night (which have now been removed).
Apparently number of minutes, texts and data of 750mb will remain the same against current monthly prices.
The two he specifically mentioned were:
£35 p/month 24 month - 600 mins, unlimited texts, 750mb data, WiFi (iPhone 4 16GB = £110)
£45 p/month 24 month - 1200 mins, unlimited texts, 750mb data, WiFi (iPhone 4 16GB = £29)
I'm not taking these as guaranteed myself so I wouldn't expect anybody else to, but thought I'd share with you all.