A part of a continuing conversation reclaiming the centrality, or rather, the continuity of writing effectively marginalized by these misleading labels (experimental, postmodern, post avant...) with modernist literature of the late 19th and early 20th Century.
One might add to Dan Green and Jonathan Mayhew's observations the importance of market driven forces in that interrupting "resurgence of realism and naturalism from the 1930s to the 1960s:" what I would call the 'late, or decadent capitalist nostalgia, represented by James Wood.
Jonathan Mayhew questions whether there is such a perceptible difference between the "modern" and the "postmodern," both in fiction and poetry, as we are sometimes led to believe. As Jonathan observes, "the term [postmodernism] took on a different meaning after Lyotard and Jameson. Basically, the word was hijacked as a term for 'poststructuralism' or for 'late capitalism,' respectively."
Jonathan suggests that poets from this period were really "continuers of a tradition" extending back to Williams and Pound, that these "new" poets' work still essentially belonged to the "modernist period." I think the same is true of what was postmodern fiction "Post-" modern meant not just after modernism but more specifically a return to the spirit of modernism understood as the attempt to expand the possibilities of form and style in fiction, an endeavor that to some extent had been interrupted by a resurgence of realism and naturalism from the 1930s to the 1960s