Play.com is now offering UK customers unlocked iPhones, regardless of whether or not they are an O2 subscriber.
Our sister site CNET UK is reporting that the handsets are usable on any UK network. The original and 3G versions are both available, with prices starting at £549.
Most of the functionality of the iPhone, barring the visual voicemail feature, should work as normal. Visual voicemail is only available through O2, which has an exclusivity deal on the iPhone in the UK.
It appears that the stock appeared at Play.com within the last week. Apple is apparently keeping quiet on the matter.