Well, the cat would seem to be out of the bag. Multiple sites are reporting that O2 posted handset prices, rates and offer details for the iPhone 3G on the Pay/Go tariff to their site, apparently late last night.
The details have since been withdrawn from the site, but are still available to us through various rumour sites and blogs which caught them.
So, how much is the handset gonna set us back? 8GB will be priced at £299.99 and 16GB at £359.99 (MacWorld UK erroneously states £400, however even their cited source disagrees). These represent modest £30.99 price hikes on the elder models.
However, O2 has seen fit to sweeten the deal. Primarily through those "top up £X each month and receive" offers, but more importantly by bundling 6 months of unlimited (3G) data. Naturally, a fair use policy is in place and the offer only applies to phones activated before...December 31st. Some time away at least.
After the bundled data period is over, unlimited data can be added for £10 a month, a neatly non-committed solution, much better than the £30 tariff.
Incidentally, the 6 Months of data is therefore worth £60. I would have been buying it each month anyway, so I like to think of it as a £300 phone (16GB model) with unlimited data at £10 a month, £60 of which is paid upfront.
At these prices, with these deals, I'm definitely going to go ahead and get a 16GB iPhone 3G with a white back. I pretty much have to now. My touch is nearing the limits because I've bought three movies, and I plan to buy at least 2, maybe 3 more.
So, all in all, I'm pretty happy.