One of the problems with the trilogy is that only one of the sites is really well defined: Stack Overflow. Questions (and answers) are programming or software development related.
Server Fault is for IT administrators and operators, and questions there are [generally] about implementing technology to fulfill some business function. This is supposed to be "server focused", but more and more IT organizations are outsourcing technology to "the cloud". For example, email is hosted by Google Apps, company blogging is done on Wordpress/TypePad. It is still up to IT to support and facilitate the usage of such outsourced technologies.
More and more companies do this, and it is perfectly valid to ask these kinds of questions on Server Fault. It may not be a clear that someone is asking because they want to implement it for their company. For the "code highlighting" question, they could be publishing blog entries about cool things their company is making. We don't know that. Rather than immediately moving a question, why don't moderators at least comment on the question, as is encouraged to get clarification about the intent.
Further, it is not valid to assume that everyone is using all three (four) sites. The person who asked that question doesn't have a Super User ID.