I always define literary as about the "why/how" you write something. In my head, anything written because it's driven by language/craft is literary. Anything driven by function/purpose, for commercial reasons (market based) or to order is (by my questionable definition) not literary. So a pb that teaches a moral lesson or instructs, written FOR that purpose, is not.
Of course, some commercial work turns out literary, and some literary work is highly commercial. But for me, as a writer, that's how I divide my work up. If I write it the way I would poetry, it's literary. If I write it as I would a freelance piece, it's not.
My picks for literary pbs: When the Sky is like lace, Eloise, Rain Makes Applesauce.
xoL