My scenario:
- Download DVD iso of F15 RC1
- make USB bootable disk with it
- disconnect computer from a network, go out where is no connection
  to internet and you know you have plenty of time to install the F15
- boot from the USB and start the installation process
- realize you cannot install, because the "configure network" step 
  cannot be skipped even you have 3.4 GB of garbage (it suddenly become
  a garbage) on the USB disk

I'm wondering who did think that the network is necessary to install system from a DVD where everything should already be. And what if my provider gets down temporarily, so I have just bad luck with Fedora? Sure thing, there are more distros to pick from...

I also noticed that I'm asked to configure my wlan0 interface, which is turned off by the hardware switch on the left side of my notebook. It surprised me a bit, but not that much to be bothered - I'm only wondering if it would give me a list of possible networks to connect to, but as I was completely without connection to any network, then I couldn't check.

Expected behaviour:
I would not configure network before install, or if you really feel that the DVD installation requires network connection then provide a "Skip" button for cases of offline installation. It might be also so clever to skip this automaticly when it detects that all interfaces are either off (my wlan0 case) or aren't connected with a cable.