In terms of window decorations, looks like twm with default settings. Standard window manager to ship with what is now Xorg.
EDIT: For emacs, those are also default colors, I think, for at least some point. X11 color names HarvestWheat and ForestGreen, if memory serves aright.
EDIT2: No, that's probably not a graphical emacs instance, because the title is "sh". They're probably running sh and then running console emacs (or vim or something else, I guess, can configure either to look like that) and don't have their shell set up to pass the escape sequences to tell the virtual terminal program to update the window title.
EDIT3: Also, the color's the default twm color, but that's not the default twm decorations. That's...damn, I can't remember the name of that widget set.
NsCDE and other CDE lookalikes seem to have a thicker horizontal bar in the upper left decoration than this and the original CDE, but perhaps that is one of the customizations the author mentions.
Also, the background seems to be from Elementary OS beta. Specifically, blueprint hue shifted to match purpleprint, based on the cropping and vignette.