I think it is indeed possible to create a Moleskine-based system. But I don't think it has to be all in one notebook. Here is how I would go about setting this up.

I would get the regular sized Moleskine (in whatever paper works for you) and divide pages into no more than four sections. So, your first ~90 pages would have your calendar. Of course, the setup time here is a bit of a pain, but it could be fun in a "you could use some baseball" kind of way. The remainder of the calendar book I would use for reference, notetaking, inbox type stuff.

At this point, there are two ways you could go:

1) NA's and projects on Index cards in the gusset pocket

or

2) in a separate notebook.

If you were to go the separate notebook route, I would make it a pocket so that you could carry it with you easier. Use index cards or post-its in the back to capture on the go.

If you go the route of getting one of the regular size notebooks, there might be the concern of running out of pages before the end of the year. I think it would be quite nifty to do a quarterly planner. So, use one of the larger notebooks for each quarter's calendar and notetaking and use index cards with binder clips for NA's and/or projects.

I left out the contacts bit just because I can't imagine anyone keeping a paper address book at this point. Your address book should at least be on your computer if not in your cell phone. Even if you don't have it on hand at all times, you should be able to trigger yourself to look up information in the appropriate context. I suppose you could put contacts in the pages following the calendar, but then you'd have to copy them over every notebook change. Too much friction for my good.

My $.02 to get the party started.

Behold, Frankenmoleskine!

http://picasaweb.google.com/mshea01/MoleskineGTDHack

It's a single book full GTD system including note cards for action lists, one Cahier for an inbox, one cahier for a weekly calendar (one week per page handwritten), and a contacts booklet. A section of the weekly calendar or the inbox can be used for projects and maybe somedays.

It's a little thicker than a normal Moleskine but it is a single full GTD implementation in one unit that fits in a pocket. Not too bad!