i've done it for 6 years running, completed all six, and will be doing it again this year. My friends always ask me how many cats are involved in each years' story...
Short samples of work don't usually count, unless the publisher is really anal-retentive. Now, if you publish it online, post the WHOLE story online... then they do have a problem. If you're posting a snippet of the first draft... oh, that so doesn't count... because it WILL change... unless they've gotten bad recently... which would be bad news for them... they're already just taking garbage for 95% of what they publish.
I do print on demand, and ebooks. Two of my books are out now. If, by some chance, a traditional publisher wanted to put me on contract and re-release said books, and future titles, they are much more relaxed now and just request that once you sign the contract, you MUST remove your self-published versions from public view. Small samples aren't as bad... they've gotten more relaxed now... at least here in the US. They know they have to work with POD published folks... or they'll die out faster than a dinosaur on crack. They know they have to change with the times... hence the dino on crack...
I do recommend to anyone doing it to NOT do POD until you've edited the manuscript at least 3 times, and sent to at least one other person who's reasonably intelligent. I see folks on NNWM every year who want to publish their Fan Fic, or something, and they're gonna doing it right away... *facepalm* those are the ones who give the rest of us POD writers a bad rep... a NNWM manuscript is a rough draft... not a finished and polished manuscript.
(rant about publishing and publishers is over... I'll try not to resurrect that)
I'm AmandaWolfe on NNWM... once the migration to the new Ruby on Rails programming is complete (that's what they're switching to), add me as a writing buddy... or you can send me a message now... mail is up...
And for the record: I have no clue if there will be any cats in this years' story... my muses love tormenting me every freaking year. And this year, they've started early... grrrrrrrr....

Amanda
(off to my other distraction of November... running stuff for a convention)