I don't really know enough about Linux fonts to answer that. The window manager, Ion, does not support Xft because its author hates anti-aliasing, so I'm not sure what is rendering the title bars -- just X, I think. The terminal font is Inconsolata as rendered by rxvt-unicode with Xft support. (Emacs is being run -nw, so it's just using the same terminal fonts.)
And for the others no links or clues as to what desktop environment or window manger is used, nor what theme, background, or distro ... basically some eyecandy with no content.
Most of them are pretty easy to tell, but many could be done in just about any window manager.
1. Not real.
2. Mac4Lin.
3. Not absolutely clear, but note that thunar's internal menus are displayed in the toolbar instead of the window, like a mac. It could be Mac4Lin again, but I'm guessing it's not real, unless there's something about thunar I don't know.
4. Enlightenment.
5. Pekwm.
6. Enlightenment.
7. Could be anything. It does have a Gnome footprint on the bottom right, though, so I'd guess metacity.
8. Fluxbox. (yay!)
9. I'm not sure. Probably compiz-fusion.
10. Could be anything.
http://disk.jrock.us/bingo/public/random/desktop-20080518.pn...
Notice how all the space is being used for actual work instead of pretty pictures. Computers are for doing things, not looking at.