Amazon have updated their Kindle Fire pages to include both ad supported ('with Special Offers) and ad free ('without Special Offers') versions. Losing the ads will add £10 to the purchase price of both the Fire and Fire HD tablets.
The change doesn't make it clear whether the ad free option can be purchased later or must be purchased with the tablet and it also remains to be seen exactly how the system works. Is it tied to a device? An Amazon account? Something else?
Hopefully we'll find out when the devices ship in the UK on October 25th.