It would be very useful to be able to include content from a section of another document. Currently, Xwiki only allows inclusion of a whole page through the IncludeInContext etc. macros. A workaround is available if programming privileges are used, by using $xwiki.getDocument() and getContentOfSection(<section_number>). Ultimately, programming privileges should not be required to support this.
Inclusion would ideally be based upon the title of the section or some other easily accesible marker unique to the section. I believe that supporting inclusion by the section number only would not be sufficient, because adding content to the page would very likely change that value. An example of the macro would be something like #IncludeInContext(PageName, SectionName) or #IncludeTopic(Pagename, SectionName).