Even writers who aren't jealous by nature can get jealous about writing. There are only so many publishers, they only have so much money. It's impossible not to feel a little competitive.
Competitiveness can be healthy. I know this, because I am ridiculously un-competitive - I blame being an only child, simply because that was my parents' choice rather than mine and thus I can pretend it isn't my fault ;) - and it can be crippling! But being competitive is only a good thing if it's healthy, loving and motivating (wow, I sounded like a self-help author there, I do hope I'm not ill). Thinking 'Oh, that person achieved that, I bet I could too!' is fine. Thinking 'That should be MINE!' and feeling vindictive is less good.
But - and I know I say this all the time - I think the new e-self-publishing revolution will take care of a lot of that. While I, and most writers I know, would prefer to be traditionally published, the fact remains that we now have something to do with the novel that gets rejected for being too edgy, too dark, too experimental, too 1980s.
You can always go digital and self-promote like mad. It's not a get-rich-quick scheme and you may sell no more than a handful of copies. But it's something. It's recourse.
And it's better than sitting at home feeling jealous :)