I don't know if you guys been following this thread or no but looks like APPLE is trying to Completely shut off jailbreak here is the thread
I Was Forced By iTunes To Restore Today, I Recieved A Notification While On My Phone
And if this does happen Well then I am so returning the IPHONE 4 cause without the jailbreak IPHONE 4 is no FUN
Here is what i found some thing from anonymous employee at apple
in the iOS4 there is a line of code we wrote that stands for OAU also known as "Over Air Updates". How it works is every 7 to 14 days We (Apple) and AT&T send a message to your iPhone that gathers some data from your iPhone without you knowing and we see what is running, baseband and firmware. We then send a following message. "There are optional updates for your iPhone, Would you like to install them now?" two options "Yes" or "Later". Those are what would would call "OPTIONAL UPDATES" Now there are things called "MANDATORY UPDATES". They tend to work the same way, grab data from the iPhones sends it to AT&T and us then back to your iPhone with the message, "Your iPhone (name of iphone) must be updated to the current AT&T standards to run", your only option is to "Accept" Now you can try to work your way around it until you get the second mandatory message again "You must plug iPhone into iTunes and update" If you don't do this you will then receive no Signal from the network anymore and your iPhone will potentially lock up with no signs of use until you update your iPhone via iTunes. You all agreed to this terms and condition when you installed iTunes 9.2 and then again once you updated to iOS4.