The Stone-Čech compactification
βX and the Hewitt real-compactification vX [6] of a completely regular T1-space
X can be obtained as certain spaces of ultrafilters from the collection of
zero sets of members of C∗(X) [4]. With the appropriate structure βX is
the space of all ultrafilters and vX those with the countable intersection
property. In this framework we give a necessary and sufficient condition for
βX × βY ≈ β(X × Y ).