My understanding of the kindle lending process currently is that we will only be allowed to lend a book once[1]. Unless they say otherwise, this model would not work. I do think that eventually this will be opened up to work like actual book lending would though. Also, remember that publishers will be able to specify whether or not books are lendable, so this may all be moot anyway.

[1] - http://www.amazon.com/tag/kindle/forum/ref=cm_cd_tfp_ef_tft_...