Just to get the first part out of the way:
http://dictionary.reference.com/browse/standard
stand⋅ard
/ˈstændərd/ Show Spelled Pronunciation [stan-derd] Show IPA
Use standard in a Sentence
–noun
1. something considered by an authority or by general consent as a basis of comparison; an approved model.
2. an object that is regarded as the usual or most common size or form of its kind: We stock the deluxe models as well as the standards.
http://moblin.org/ -- based on Gnome stuff
http://maemo.org/ -- Gnome stuff.
Debian -- Largest and oldest non-for-profit Linux distro in existance. Default desktop is Gnome.
Ubuntu -- Currently the most popular desktop distro. Based on Debian. Default desktop is Gnome
Redhat/CentOS/Scientific Linux/Unbreakable Linux/(and other Redhat clones) -- The premier 'Enterprise' operating system for large businesses that require support from a vendor and certified platforms for running their software. Default desktop is Gnome.
Novel's Linux systems... Novell desktop, OpenSuse, SLED, etc etc -- The secondary 'Enterprise' operating system for large businesses (etc etc). Default desktop is Gnome.
Fedora -- Most 'cutting edge' distro. Essentionally a playground for developers and is used for testing software for inclusion into future Redhat releases. Gnome by default.
etc. etc. etc.
'Standard' as in 'most common' the 'default' etc etc.
Most of those systems can run KDE just fine. Just like they can run LXDE, XFCE, Fluxbox, or half a dozen other desktop environments. But Gnome/GTK is going to be the most common.