The project wikibooks does not seem to be enjoying the same sort of growth that the original wikipedia did. There are probably a number of reasons for this. I shall give a few reasons I think are important and then follow up with some suggestions for the action that could be taken to remedy this.
1) Wikibooks requires a different logon to wikipedia. IMHO it would be better for the project if existing wikipedia developers could be automatically part of wikibooks. This would allow more free movement of labour from wikipedia to wikibooks. A strong motivating factor for people developing in wikipedia is the racking up of credit in the form of edited articles. Why not allow create a contributions page that gives credit to all material worked on in any wiki project?
2) Wikibooks is not interconnected in the same way that wikipedia is. There is a clear need for a different structure to the books as they are meant to be (at least eventually) printed and should therefore have a linear style. However, if links were made in such a way that they could deleted without interfering with the quality of the text then we could have the same interconnection that wikipedia has without that necessarily causing problems with the style of the books.
We need a way to designate sections as being developer areas (but within the actual text itself) We could produce a special heading "Developer's notes and links" which has a template (to ensure consistent usage. We need a special link type that represents a temporary link for development purposes. This would allow the developer links and comments necessary to speed up development. But at the same time would allow these links to be removed with ease when the wikibook is downloaded. (Of course links just to wikipedia should be fairly easy to remove automatically although it might help if they appeared in a different colour to remind developers that that material reffered to will not be available to the readers of printed versions. 3) Also links can be made from relevent pages of wikipedia to wikibooks. This should draw in much more labour to liven up wikibooks. This is one thing that I can implement on my own. So I shall start introducing a section on some selected wikipedia pages entitled "relevent wikibooks". I may also start links to wikibooks in the main text of some articles in wikipedia. However, without 2) we may find that people learn to ignore links to wikibooks as they are deadends.