No simple way, since every ePub has both a table of contents file (toc.ncx) - and an index file (content.opf)... the first would take a bit of time... but the latter of which has a playlist, which would be incredibly irritating to re-order. Rename an epub as a zip and take a look... You'll agree it's probably not worth the effort...
Edit: I just realized the number of your posts. You're unlikely to be a n00b... but even in creating my own ePub's I was frustrated whenever I had to go into either of these files. I'm sure a program could be created to merge ePubs but again, it's probably not worth the effort... And yeah, I'm sure you're not the only one who thinks these authors need to compile their short-stories into actual books.
Last edited by darkpoet; 03-11-2010 at 08:31 PM.