Yesterday Apple released a patch for the security hole in Safari. This was the same hole which was used for the "Jailbreak Me" Jailbreak which was so easy to use.
The security hole had to do with the way PDF files were handled, and was quite serious. The Jailbreak community released a "PDF patch" of sorts - basically a warning every time a PDF was opened on iPhone a dialog pops up with a warning and an OK and Cancel button. This patch made reading valid PDFs in various applications, including iBooks, unusable. It also made using the Zinio reader - which is a reader for digital magazines like PC Magazine, unusable (four popups for one page). So the patch was updated to allow iBooks to work, but it was a kludge and I wondered if the developer would get round to the Zinio reader.
I was beginning to wonder about either uninstalling the PDF patch - and opening up my iPhone to hacking, or updating the firmware, which would fix the PDF security hole but then I wouldn't be able to Jailbreak my iPhone probably until after iOS firmware 4.1 is released.
Anyway, today Saurik released a patch which basically does what the Apple iOS 4.02 firmware update does - patches the PDF security hole properly, and the Jailbreak stays intact. Thank you Saurik (and whoever else helped to code this patch)!