AT&T is cutting up to 6 months off of the usual 18-month service commitment before allowing a free upgrade to the iPhone 4 which will be released on June 24th.
Since the iPhone 3GS was released last June, that should make anyone who bought one, and would like to get their hands on the newest model, applicable for the upgrade after 12 months, with an US$18 upgrade charge, which is right about now.
To find out when you can upgrade without a penalty you always could dial: *NEW# on your iPhone which will generate a text message telling when you can upgrade. I just did, since I bought my iPhone 3GS the day it was released last June, that and the text message that was sent to me said that I wouldn’t qualify until 2/20/2011. This made very little sense in light of the new policy, so I called up AT&T to find out if I was applicable. They didn’t know, telling me that since this is brand new information, it hadn’t gotten to them yet. But they made a commitment to call me before the release date on the 24th. So, if you think the text message information you get is wrong, wait a few days before you call AT&T, so they can let the information filter into their system.