Apple let loose with iOS 4.02 yesterday which added no features at all, but plugged the PDF exploit in Safari browser that comex and the www.jailbreakme.com team had used on 4.0 and 4.01 to gain full control over the iPhone.
So what does this mean? If you want a jailbroken phone, don’t update. If you don’t want a jailbroken phone, update and feel a little more secure using Safari.
The PDF flaw, ironically, was monitored by an application available after jailbreaking.. So, another route you can go if you’re just worried about security, is to actually use the PDF exploit via www.jailbreakme.com and then load the app on Cydia called “PDF Loader Warner”.
I’m sure that Comex and crew will have a new Jailbreak method in very short order, but if you’re still on 4.0 or 4.01, I highly recommend that you jailbreak with the current method since it’s DEAD SIMPLE.