JailbreakMe on iPhone 4, 3GS and iPad. This jailbreak is done directly on your phone using Safari, so you do not need to connect it to the PC. Total time is under 5minutes.
On safari, go to http://Jailbreakme.com, slide to Jailbreak and enjoy.
This works on almost all devices running the latest software as of August 1st, 2010. In the video we use an iPhone 4 running iOS 4.0, iPhone 3GS running iOS 4.0.1, and an iPad running iOS 3.2.1.
For this video in other languages, check out:
Japanese: http://AppGirl.jp
Spanish: http://AppGirl.es
English: http://AppGirl.tv