the Application development guide would be great..
But to answer the basic guide question..
The obvious one would be to cover install, from fresh with the distro, and also adding it from an existing installs repo's/package management.
Initial setup, and a howto on using the interface.. i.e. click on the activities to bring up the shell.
Howto on finding and launching the programs for everyday use., web, email, office etc.
how to change basic settings, like keybnoard screen, wallpaper.
then move into the more advanced. Install extensions, change themes.
Although alot of us would easily be able guess how to do this if we had never seen Gnome 3, alot of users wouldn't
for example.. I upgraded my main PC to Gnome 3 , and my wife tried to use it.. she sat looking at it for around 5 mins wondering how to get on the internet. She gave up and rebooted into Windows.
The following day she borrowed my laptop that has gnome 2 installed, and she immeadiatly clicked on the menu to get to the programs list and was on the net in seconds..
For some users the new interface is quite a change, and they need to be hand held thru it.
Once I showed her how things work in G3, she is now very happy to use it.
Don't Dream it....Be it.. Xubuntu...