There are 8 SPUs on the Cell, but the PS3 dedicates one of them to hold the Game OS. Another one is blocked off because IBM was having yield problems.

So the poster is right. Despite the presence of 8 SPUs on a Cell, only 6 are available on the PS3.

And there's actually a book available on programming the Cell (particularly on the PS3). It's here.

If he was alive today, we'd call him a zombie...

Prime Obsession: A well-written history of the still-unproven Riemann Hypothesis. Maybe one of your students will solve it over summer break!

Actually, there are eight SPEs, but the PS3 only allows users to access six of them.