I have been using it on a side project for the last week and I really like it!

However, to me the distinctive feature of a blog is not that, but the way entries are ordered (i.e. reverse order by date). For a manual, faq, feature requests,... I need a different ordering scheme, but I am happy with the "one main content" concept.

That having said, there is of course a need combine content in a single page. A layout (aka template) can combine content as needed. It can use other attributes of the page, specified in the front matter. Or it can use the content from other pages. One could put subpages in a subdirectory, and use some filename convention so that a layout can access them.

Urubu has support for pages that are only present for content, and not for being rendered themselves: you can specify a 'null' layout in the front matter.