Finally updated my iPhone3gs to iOS 4.0.1 after confirm with my friend that it’s able to jailbreak. Finally can play around with the Folder categories and multitasking of iOS4.
To jailbreak your new installed iOS4, just open the safari browser and visit the website http://www.jailbreakme.com or http://jailbreak.modmyi.com. After that, just follow the instruction on the screen and it take less then 5 mins to jailbreak it. After all, you will found that cydia already install in your new iPhone iOS4 page. Please take note that your phone must be able to connect to Internet either using wifi or 3G.
The most easy way for jailbreak ever