In Pages, Numbers, and Keynote, the support for OpenType features comes from the OS.
In Snow Leopard, the smcp and c2sc features were listed under Letter Case > Small Capitals and Letter Case > Small Capitals from Capitals. And they worked.
In Mountain Lion, these features are now called Lower Case > Small Capitals and Upper Case > Small Capitals. But they don't work.
This seems to be strictly a GUI bug, since a document made on Snow Leopard with smcp or c2sc will still show those features properly when opened on Mountain Lion. But the OT panel won't show them as being activated.
Comments
H&FJ also mention Small Caps not being supported in those apps in their OpenType support table: http://www.typography.com/ask-hfj/opentype/#otfchart-grid