Why is Sitepoint made a JQuery book but doesn’t have a dedicated JQuery area, it makes no sense to me.
jQuery is JavaScript, so I guess questions/comments/discussions should slip into that forum.
Would you expect there to be a Symfony forum in the PHP area, why not a Dojo forum to go alongside the jQuery one, or <insert framework/library> in the <insert programming language> forum?
Exactly. jQuery is just 13k of JavaScript and so asking questions about it is no different than asking questions about any other JavaScript.
Yes and no. Yes, it is javascript so such questions would fall there. But I think you can make the argument at this point that there is so much jquery-specific development going on that it could make sense as it’s own sub-forum, such as the mysql subforum for the databases section.
If I remember correctly it was discussed a while ago as to whether to separate out jQuery into its own sub-forum. I think the conclusion was that there is too much overlap with ordinary JavaScript code to justify it.
From the jQuery questions I have seen, a good percentage of the time a few lines of simple JavaScript would resolve the problem without jQuery.
That was the case 
There were not enough jQuery specific questions to justify it… and most of the time it overlapped with regular javascript so it was easier to keep everything under javascript