3D or 4D plot

I have data on a regular grid in the format: x  y  z data. I would like to
be able to plot them in 3d kind of like a volume or a mesh with colors. Is
that possible in R and how?

There are lots of ways, depending on what you want the plot to look 
like.  One is

library(rgl)
plot3d(x, y, z, col=color)

(assuming you also have a variable indicating the color to plot).

Duncan Murdoch