If this turns out to be true, then this might be the most conclusive evidence of an impending 3G iPhone launch we've seen yet. A blog post at the Chronic Productions Blog writes that firmware 2.0 Beta 5 Network.plist file contains prefrences for 3G networks that can be activated somehow. Screenshot and transcript after the break.

From the blog:

Note that this is not fake, it is in the beta 5 .ipsw, but will normally not show up on an EDGE iPhone. Turning 3G on will just crash the phone if you use an EDGE phone. If you do not believe me, then decrypt the beta5 rootfs dmg, and see for yourself in /Applications/Preferences.app/Network.plist

[Chronic Productions Blog (1, 2) via MacRumors]