Surely there are enough people with a serious, technical interest in FAI and related topics (and I don't just mean among LW regulars) to make such a channel sustainable.
Vast majority of IRC channels are ghost towns, with virtually no activity after the initial burst. You will have to achieve some critical mass to make a channel viable. Be prepared to announce and give periodic seminars and champion the channel in other ways if you want it to live. And yeah, ##FAI is the way to name it.
Under freenode's channel naming policy, I think ##FAI (two hashmarks) is more appropriate.
I visited #lesswrong on freenode yesterday and was able to get in some discussion of FAI-related matters. But that channel also exists to allow discussion of rationalist fanfiction, political opinions, and whatever else people want to talk about.
I would like for there to be a place on that network where the topic actually is Friendly AI - where you can go to brainstorm, and maybe you'll have to wait because they're already talking about cognitive neuroscience or automated theorem provers, but not because they're talking about ponies or politics.
Surely there are enough people with a serious, technical interest in FAI and related topics (and I don't just mean among LW regulars) to make such a channel sustainable. I'll bet that there are other people holding back from participation precisely because existing forums are so full of uninformed noise and conversational tangents. It's inevitable that entropy would set in after a while, but if the default baseline was still that even the chatter was technically informed and focused on what's coming - that would be mission accomplished.
I explored the freenode namespace a little. #FAI redirects to #unavailable, so it may be an abandoned project. #AGI exists but is invite-only. #AI exists but I'm told it's dull, and besides, the agenda here is meant to be, not just AI, but singularity-relevant AI. So there seems to be an opening. Or am I reinventing the wheel?