Yep, it appears to be limited to once and for a two period only in which the purchaser cannot read the book.
http://www.amazon.com/tag/kindle/forum/ref=cm_cd_ecf_tft_tp?_encoding=UTF8&amp;cdForum=Fx1D7SY3BVSESG&amp;cdThread=Tx1G2UIO9PJO50V
A shred of hope that the spirit is maintained then...