Image from BGR
One of Boy Genius Report's sources at Apple has informed them that deep within iOS4 is a block of code that queries the device. It's normally used for iDevices in field testing to bypass the need for iTunes activation (as any owner of an iDevice is familiar with at this point).
Meaning that the device in question may be the CDMA iPhone or an updated iPad. This chunk of code has been used every year before previous iPhone updates for, you got it, field testing. Note that the piece of code is removed when the device gets launched.
Field testing is the stage in which phones are taken to real-world settings in order to see how they work in a regular environment. The infamous iPhone 4 that Gizmodo got their hands on was being field tested when it was lost.
This fits very well with what Daring Fireball reported last week. The Verizon iPhone may be right around the corner.