Just two words: Alloy Entertainment.
It gets curiouser:
The relationships between Alloy and the publishers are so intertwined that the same editor, Claudia Gabel, is thanked on the acknowledgments pages of both Ms. McCafferty's books and Ms. Viswanathan's "How Opal Mehta Got Kissed, Got Wild, and Got a Life." Ms. Gabel had been an editorial assistant at Crown Publishing Group, then moved to Alloy, where she helped develop the idea for Ms. Viswanathan's book.
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Update (3 May 2006): There is more from Washington Post, Boston Globe, Harvard Crimson, and Crimson (again). The last one is about the book being yanked for good. The others dig up more dirt on the plagiarism front (she has plagiarized at least two others: Sophie Kinsella and Salman Rushdie), and on the 'packaging' front.