iPhone 4 Jailbreak Now Available: with JailbreakMe 2.0, No Computer Required.

JailbreakMe 2.0 is a browser based jailbreak, all you need to do is to browse the Jailbreak Me website at http://jailbreakme.com from your device(iPhone 4, iPhone 3GS, iPad...) and successfully load the page.
List of supported devices:
iPod 1G on 3.1.2
iPod 1G on 3.1.3
iPod 2G on 3.1.2
iPod 2G on 3.1.3
iPod 2G on 4.0
iPod 3G on 3.1.2
iPod 3G on 3.1.3
iPod 3G on 4.0
iPad on 3.2
iPad on 3.2.1
iPhone 3G on 3.1.2
iPhone 3G on 3.1.3
iPhone 3G on 4.0
iPhone 3G on 4.0.1
iPhone 3G[S] on 3.1.2
iPhone 3G[S] on 3.1.3
iPhone 3G[S] on 4.0
iPhone 3G[S] on 4.0.1
iPhone 4 on 4.0
iPhone 4 on 4.0.1
if you're antsy about such a maneuver, at the Redmond Pie, will have some how-to guides handy for you.

Via gizmodo