First Publication Rights

[MJRevell]

If I post work on a website such as this one, it will obviously mean I can't send it to magazines who want first publishing rights ... but how far does it extend?

If I write a story, post it up online, then change it (and add in, say, 1000 more words) so that it's an entirely different beast -- are the rights still given up? Will magazines still not want any part of it?

[chopper]

as far as i'm aware, it depends on how much of any given story you post for critique here/elsewhere, just as the Critiques FAQ makes careful note of. i would certainly not wish to post an entire story up here.
Chronicles doesn't lay claim to any publication rights either, but as you rightly point out, most markets won't look favourably on a story that is already freely available online.
if you're posting a very rough first draft, and the story changes quite substantially on its way to a finished form, then there shouldn't - theoretically - be a problem in posting excerpts here (or on the passworded AbsoluteWrite forums, for example).

my 2p.

[Tirellan]

If the site is password protected then you have no problem