I should think that any fabric of uniform color that provides good contrast
with the subject would work. Elements 3.0 has the "magic wand" tool to
select by color. You can widen the tolerance, but a wide tolerance increases
the chance that you will select something in the main subject.

Owl

  I believe any solid color will work, they just normally use the bright  
green because people don't often wear that shade of green. Fabric should  
work fine, I would think, provided it's not to close to any colors in the  
subject.

Kelly

Well these colors (blue and green) were originally designed to
register in only one channel of a video camera. Presumably they will
have a more-or-less similar effect on a digital still camera. Modern
digital processing is presumably less finicky on the exact color used,
but, as others point out, the special colors will presumably do a
better job of avoiding other colors in the image.

Any solid (no mix of colors in weave) color that contrasts well with the
subject should work well.

Even lighting of the backdrop is very important.  If you have graduated
lighting on the BG, you will have color variation that will make
separation more difficult.

Have fun, just don't expect it to be 1,2,3 easy.

PS CS does a better job of this than E3.0 for reasons I don't remember
the details thereof (so I've been told).

Google away before committing a large shoot.

Cheers,
Alan.