[R] Points on a Sphere -- How to visualize them?

[Lorenzo Isella]

Dear All,
I need to do something simple: I have a set of points which are located on  
the surface of a sphere (let's say the centre of the sphere is in (0,0,0)  
and the sphere has radius R=1).
How can I visualize them?
I am looking for something like this

http://bit.ly/PnSerU

with the addition of some spots that represent some points I want to plot  
on the sphere surface.
Any suggestion (and in particular example) is really useful here.
Many thanks.

Lorenzo