Three, Orange and T-Mobile are offering the phone for free on contracts of £35 per month. If you're into shiny, exclusive stuff then you'll be interested to learn that T-Mobile will be exclusively selling the silver version of the device (that's the one in the pic above). If you order a Desire S through any other carrier you'll get the standard black version.
Vodafone and O2 offer a free Desire S on slightly cheaper contracts of £30 and £27 per month respectively. Meanwhile The Carphone Warehouse can hook you up with a free Desire S on-contract with a number of providers for as little as £25 per month.
If you're thinking of picking up a Desire S, make sure you check out our hands-on feature, and keep watching over the next few days for our full review!