Either they have or Amazon decided to ignore GW's request - as M.C.A. Hogarth's book Spots the Space Marine is back up for sale on Amazon.com.
Having a fairly negative report from the BBC, as well as whole host of authors pillorying your position (Cory Doctorow, Charles Stross, John Scalzi and Neil Gaiman) may have made someone rethink the decision -and rightfully so.
Given GW's fairly liberal borrowing of concepts and terms (Eldar is straight up Tolkein, Lasguns are in Dune etc) it saddens me to see them take this move. Given the strength of the 40k Space Marine image, would GW really lose that much if the trademark lapsed? I'm not convinced they would.
If you don't want to go through Amazon or don't have a Kindle, Smashwords also has the book available (and has sample pages).
EDIT: Games Workshop have issued a quasi-official response via Facebook.