It was first published in Amazing Stories, September 1993, and reprinted in Di Filippo’s 1998 collection Lost Pages.
Thank you. To Amazon and Away!
There is a much faster way to find out where any science fiction or fantasy story has been printed than by asking on the SDMB. Go to the Internet Speculative Fiction Database (which you can find just by Googling on that name). Enter the name “Paul Di Filippo” and then the title “Campbell’s World” and you will get the following webpage: