The Movies StackExchange site is now available to the public. If you’ve got questions that need answering by a film expert, then this is a good place to ask.
There don’t seem to be many sci-fi or fantasy movie questions yet, but if you’re particularly interested in or expert in film, then you might want to keep an eye on the questions there (if you’ve got an account on our site with at least 200 reputation, then if you associate the two accounts – you’ll be prompted to do this if you use the same OpenID – then you’ll start off there with 101 reputation).
If you’ve got a question about a science fiction or fantasy movie, where do you ask that question, now that there’s both sites? Consider who you would like an answer from: an expert in science fiction / fantasy, or an expert in movies in general; different types of questions will suit each site. Some questions will be perfectly acceptable on both sites, and in those cases it’s up to the asker to decide where they’d like to ask (in general questions won’t be migrated between the sites, and duplicates may exist on both sites, as long as they are not exact duplicates). You should definitely not post the same question on both sites, however.
Also, don’t forget that there’s a similar site for the written word, Literature, where there continue to be a reasonable number of science-fiction and fantasy literature questions, aimed more at a literature audience than a sci-fi/fantasy one.