Wow, turns out it's Yahoo that's doing no evil this time:

The key difference: Yahoo is not scanning copyrighted works, as Google did before publishers called foul and it temporarily stopped. Instead, Yahoo is paying for the scanning of older, out of print titles and making them searchable through the Yahoo index and a new website at opencontentalliance.org.

If they're smart, they'll be creating/using some sort of standard so that copyright owners can create concordances, etc, that can interoperate anonymously. That is, if you want to make your book Yahoo searchable, you simply follow the standard and you're in the system.