Hi Guys,
I have been doing some reading of VRP papers and added some links to wiki page.
Of particular interest is A general heuristic for vehicle routing problems:
http://www.diku.dk/users/sropke/Papers/GeneralVRP_TechRep.pdf
This paper shows how to map VRPTW, CVRP, MDVRP, SDVRP and OVRP problems to a Rich Pickup and Delivery problem with time windows (RPDPTW) problem. Being able to map problems from one problem to another provides a lot of insight to how these problems are related and how we can possibly use a single solver and some mapping to solve different problems.
I think these ideas are directly related to both of our GSoC projects this year. I'm not suggesting that you implement this, but you might want to take some of the ideas here and use them in your designs to allow for future development and some might be directly implementable.
-Steve