Pricing has not be announced for the 3G iPhone in the U.K. but O2 has something special already prepared for existing iPhone customers. Quote below:

The 8GB model will cost just £99 on a new £30 per month tariff and the existing £35 per month tariff. Consumers choosing either the £45 or £75 per month tariffs will get the 8GB iPhone 3G for free.

The 16GB iPhone 3G will cost £159 on the £30 and £35 tariffs, £59 on the £45 tariff and it will be free on the £75 tariff.

All customers will continue to receive unlimited data browsing over O2’s HSDPA network and unlimited access to 9,500 Wi-Fi hotspots through both The Cloud and now BT Openzone.

Both the 8GB and 16GB iPhone 3G will also be available for O2 Pay & Go customers with pricing to be confirmed in the coming weeks. Fit for Business iPhone 3G will also be available on current O2 business tariffs as a monthly bolt on, with the device available for free on the majority of business tariffs on a 24 or 36 month contract.

Yes, I know, we all hope our own exclusive iPhone distributors in our respective territories offer free iPhones, too.