I think it's a good idea, popmuze, and certainly don't see how it could hurt.
Probably no single one of us knows enough about what specific editors are looking for at any given time - but if we all shared what we knew when we knew it, surely some of it would be helpful to somebody.
For instance, for a single period of three weeks last year I knew exactly what two specific editors at Bloomsbury were looking for (and it certainly wasn't something you'd guess), I knew what a new editor at John Murray was hoping to find to expand their range, I knew about Harper Collins, Orion, Hodder Headline and one specific editor at Penguin. Now, of course, all that is useless - they'll have all found what they were looking for and moved on. But if I'd been a member here then and posted what I knew (no breach of confidentiality involved) mightn't it have been useful to someone who happened to have written exactly what was being sought?
Of course, the agent argument still applies - none of these people would have looked at unagented submissions, and by the time an m/s made its way upstairs to them from the slushpile the moment might have passed. But I'd say:
1) Even a good agent is always on the look-out for the kind of inside info I'm talking about, and I can't imagine mine minding if I said 'I've just heard X at Y is desperate for something like this, should we try them as well?'
2) Even from the slushpile, one might make quicker progress if one were able to tap into a specific demand. Your query would be addressed to a very specific person and would use the exact phrase of what you know they're looking for - it's possible (maybe unlikely, I don't know) that a clued-up assistant would look at it quicker than others in the pile because they know it's what the boss is looking for.
I don't know enough about the industry to know how helpful all this would really be, and certainly don't know the US publishing scene at all. But if that's the kind of thing you had in mind, popmuze, I don't see the harm in it. If we had a thread like that, I'd certainly post in it whenever I heard anything that might be useful to others.
Louise