No, it is not avalable now cause there is no any unlocked 4g till now, and waht you have to do is wait,ok?. The details of this 4G, you can visit my blog, and i am sure you will get more? Thank you gain.
No, you can not jailbreak it now cause there is no information of how to do this right now. About this you can see my blog, there are lot of specific details of the real functions of 4G. Thanks again!
I can confirm that there is no jailbreak or unlock available at this time. But the iPhone Dev Team has developed one and will release it soon. I assume they will wait until Apple releases Firmware 4.0.1 and/or until iPhone 4 is available worldwide.