Update: It turns out that the three contracts are for 24 months, thanks again to @loosend for the information
Three has finally announced their pricing for the iPhone 4 for the UK, prices start at £99 for the iPhone 4 16GB on £30 a month contract, and the contracts are 24 month contracts.
The 32GB iPhone 4 will cost £189 up front on the £30 a month contract, and with both these contracts you get 500 minutes, 5000 texts, 5,000 three to three minutes and 1GB of data.
Three have also announced some SIM only tariffs for the iPhone 4, there is a £15 a month rolling one month contract which will get you 300 minutes, 3000 texts and 1GB of data, or a £25 a month contract which is a 12 month one that gets you 2,000 minutes, 5,000 texts and 1GB of data.
The SIM only plans will be available from Three from tomorrow the 25th of June, there are no details on when the iPhone 4 will go on sale on Three as yet.
Thanks @Loosend for the tip