The cat is already out of the bag as "first-sale" disappeared years ago as it relates to software. All software is sold under license and if you read most EULAs you are prohibited from selling or giving it away. It would seem that everyone has meekly bought into this idea and it was only a matter of time before it was applied to ebooks, which, one might argue are a form of software.
There is an excellent summary of the issues related to first sale at http://en.wikipedia.org/wiki/First-sale_doctrine
. I was not aware of the Clayton Act nor that some aspects of EULAs are unenforceable in some states.