This topic gets talked to death on my forum and I'm curious what photographers here think about it. A lot of art shows specify in their applications that photographs should be numbered in editions of no more than 250. Personally I don't believe in editioning and feel it's a ploy to limit photography and was started by painters putting pressure on art shows because they weren't allowed to sell lreproductions.
I did some research on the subject last year and discovered that Cartier Bresson never numbered his prints, and never printed either. Yet he his photographs sold for the highest amount of money (when he was alive) of any living photographerm starting at approximately $7,000 for an 11x14.
Here's an essay I wrote on the subject titled Photographys Role in the Art World.