I reckon we can actually do most of that with a non-invasive shell-script. It might not be as smooth turning things on and off, but off the top of my head:
* Username: Can be do with 'chfn -f' or policy-key equivalent
* Datetime: do-able with Popey's (double) gsettings hack
* Network: dpkg-divert/override *all* of the network related icons to be wifi-max
* Battery: dpkg-divert/override *all* of the network related icons to be battery-max
* Background: gsettings overwrite org.gnome.desktop.background picture-uri
* Launcher: gsettings overwrite com.canonical.Unity.Launcher favorites
It would significantly hackish, but we could knock a shell-script/mini-package that uses dpkg-divert up before 12.04 LTS release.