They've already posted a hands on video showing the Siri settings.
In these photos, the iPhone 4S is on the left, iPhone 4 GSM middle, and iPhone 4 CDMA right.
The photos simply show the new antenna design of the iPhone 4S which looks almost identical to the CDMA iPhone. The only noticeable difference is the addition of a GSM slot. Otherwise, the phones appear identical on the outside.
AppVV has further shots, but you need to be a registered user.