So it turns out that what make JailbreakMe work so well is a font bug existing in Adobe .PDF files (http://twitter.com/0xcharlie/status/20162123890) which the iPhone is set to automatically download and open. What's worse, the bug seems to have come from Apple's own PDF rendering engine. This means, in theory, that any PDF file with the bad code could be tweaked to do worse damage than just a jailbreak.
Luckily, Will Strafach (@cdevwill) came up with a safety fix: a .deb file that you download to your PC or Mac's /var/mobile directory, then install on your jailbroken iPhone.
To install on a Mac via Terminal:
- ssh root@your IP address
- dpkg -i file.deb
Where "alpine" is the default password you'll get after installing Open SSH from Cydia and "your IP address" is located under Settings – > Wifi – > active wifi connection.
To install on a PC via iFile, navigate to the /var/mobile directory and double-click on the .deb file.
Once installed, the fix will prompt you to confirm every time your iDevice attempts to open a PDF file, manually or automatically.
[Via MacStories ]
Accessories & Apps: Beta Testers Wanted
iOS Firmware/IPSW Download Guide
Legacy iTunes Download Archive
App Store Top Charts
iPhone and Android Resale Value Charts
USA iPhone Carrier Plans Compared
Complete iPhone Jailbreaking Guide 
Complete iPhone Specification Matrix 
So… Essentially… We have to jailbreak, to fix an Apple security flaw that can compromise our phone?
How Ironic
I installed the PDF Loading Warner via Cydia & I now get the PDF Loading Warner screen when I open the apple clock icon
Ironic doesn’t begin to cover this. One the one hand, thanks Apple for the exploit that (at long last) allowed a public release of a jailbreak for iPhone4, but on the other hand… scary.
Yay!! I’ve been waiting for this one!
I like the jailbreaking spirit.
I just saw other article about Jailbreaking for iPad from aneesoft. some people who want to know more can read it.