iPhone os 4.0 now?

nobody in the hack section

is likely to want to try 4.0. We are having enough fun with all the accidentally upgraded to 3.1.3 let alone worry about 4.0 there is nothing Apple can bring to the table that we don't already have better with Jailbreaking!

Mutitasking
App control
3G Unrestictor
Mywi
Lockinfo
Themes

On and on! imo I'd be crazy to want 4.0 right now oh wait I get commercials and a Winnie the poo book! I'm going to try it now!

 

before anybody can answer

need to know what phone you have and firmware. if I were you I'd do research there tons of threads on Jailbreaking and tutorials start with the stickies at the top of this section!

 

4.0 won't run on your phone without a developers account and there is no downgrading down from 4.0 as the hackers have posted.

I don't know if I would trust their activation if you can't get out of it. There is already a thread here for someone asking for help to downgrade because he is stuck on 4.0 beta.