Upgrading from:

Graphics`Polyhedra`

PolyhedronData has been added to the built-in Mathematica kernel.
A new Polyhedron Operations Package has been created.

New system function

PolyhedronData has basic information about named polyhedra:

Version 5.2 << Graphics`Polyhedra`;
Show[Polyhedron[Octahedron]]

Get the list of coordinates for the vertices of an octahedron:

Version 5.2 Vertices[Octahedron]
Polyhedron Operations Package

Many functions from Graphics`Polyhedra` are now found in the Polyhedron Operations Package:

Stellate Geodesate Truncate OpenTruncate

Generate a stellated octahedron:

Version 5.2 Show[Stellate[Polyhedron[Octahedron]]]

GreatDodecahedron, GreatIcosahedron, GreatStellatedDodecahedron, Polyhedra, and SmallStellatedDodecahedron were available in previous versions of Mathematica and are now available on the web at library.wolfram.com/infocenter/MathSource/6822.