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.