C.T.
I recall recently (less than 4 months ago) reading about organic mattress in two articles in the NY Times.
The first was for infant crib mattress: http://www.nytimes.com/2009/01/15/garden/15mattress.html?...
The second for regular adult mattress: What Lies Beneath? By JULIE SCELFO Published: January 15, 2009 (I could not seem to pull up the rest of this article... maybe your local library would have it).
When I did a word search for "organic mattress" at NYTimes.com, I also found this article "All-Natural Bedding: Counting On Sheep, Cotton and Even Milkweed ". This is not the one I was thinking of the two above are, but maybe it will help you.
Good luck.
~C.