Update

Okay here's the update from Publishers Weekly:

Readers who have a copy of Kaavya Viswanathan's How Opal Mehta Got Kissed, Got Wild and Got a Life may want to hold on to it, as the book is now a collector's item. In a statement issued from Little, Brown, the publisher finally said that it will not be releasing a revised edition of the book. And Viswanathan's second book in that two-title deal she signed with LB is dead too. The brief announcement came this afternoon from LB's senior v-p and publisher, Michael Pietsch.
While LB would not comment on what this means for the highly publicized $500,000 advance the young author received, agent Robert Gottlieb told PW that it's certainly possible the imprint could request that the money be returned.

The article goes on to say that LB could sue Viswanathan but that's unlikely.

Suing would really take up too much time and resources. Get the check back and move on.