I know for sure that you can do this with the 3D modeling and particle program XSI from Softimage, wchi gives you a “stick to layer” function. Particular is difficult because I don’t believe you have a lot of control over one particle for an extended period of time … and that’s what you need to make them move from one shape to another.
You might be able to generate somewhat of a similar effect in particular by creating a reference alpha layer that shows the shapes (white on black) morphing from one to another. The problem with particular is that it uses this information as a generation point for particles, not a target point for ones that already exist.
Good luck with your project. I’d like to know how you figure it out.