A much-improved version of xpost2 is available at
http://code.google.com/p/xpost/downloads/list
Includes (by *no* special arrangement)
escher.ps (found in comp.lang.postscript)
tiger.eps (liberated from the ghostscript examples)
fern.ps (looted from Don Lancaster's massive Postscript Repository)
all of which xpost successfully executes.