Orange are selling the iPhone 3GS 32GB model for the same price as the 16GB model for this weekend only. It is only in retail stores for this weekend only and they are offering half price accessories iPhone. It is an 'under the counter' offer so they may not offer it by default but if you push it there's no reason why they shouldn't give it to you. This offer expires at close of business bank holiday monday.
I know a lot of people on here dislike 24 month contracts but none of the networks budge on iPhone so this is a great opportunity!