In the case of JailbreakMe 2.0 (the exploit last year), the makers of the JB actually released a Cydia patch for that exact reason. In that instance, the JB'ed

In the case of JailbreakMe 2.0 (the exploit last year), the makers of the JB actually released a Cydia patch for that exact reason. In that instance, the JB'ed device was in that regard more secure than the stock device.