Phones 4U are the first out of the gate with pricing, offering to take either your first born child or a whopping £46 a month for a free Galaxy Nexus over 2 years. If that's a little too much on the ridiculous side (yes it is) then you can go a whole £5 cheaper at £41 per month if you cough up £29.99 for the phone up-front. There's definitely going to be more diverse pricings...at least their better be, nobody will spend near on £50 on a phone contract...except iPhone 4S owners (see the UK pricings here).
UPDATE: Vodafone, Three and O2 have also confirmed they will be offering the new Nexus, although so far there's been no mention of prices -- safe to say though, you can expect it to float somewhere around Phones4U's pricing. We expect to hear announcements shortly from Orange and T-Mobile about their deals.