The end of the Harry Potter books certainly hasn’t meant the end of J.K. Rowling’s busy schedule. Last week Rowling and Warner Bros. issued a response to a filing by RDR Books, the Michigan publisher that plans to release Harry Potter Lexicon, based on material posted on a Harry Potter fan Web site. In the lawsuit, originally brought by Rowling and Warner Bros. last October 31 in Manhattan, Rowling claims that the proposed RDR work will infringe on her intellectual property rights and threaten the sales performance of her own definitive Potter guide, a book she has long intended to create, with its proceeds going to charity. RDR maintains that Rowling’s acceptance—and, often, praise—of free Potter fan Web sites, justifies RDR’s efforts to publish the book by fan site editor Steve Vander Ark.

This latest round of legal paperwork also includes statements from Suzanne Murphy, publisher of Scholastic’s trade division; Cheryl Klein, senior editor at Scholastic; Sarah Odedina, publisher of children’s books at Bloomsbury in the U.K.; Neil Blair, junior partner at Christopher Little Literary Agency; and William Landes, professor of law and economics at the University of Chicago Law School. A hearing on the matter is scheduled for March 13, at which time Rowling and Warner Bros. hope a preliminary injunction will be granted.

But for fans, the most significant of Rowling’s post-Potter activities is that she’s begun writing again, even frequenting some of the familiar haunts where she spent hours crafting Harry’s adventures. The Mirror reports that Rowling is working on some children’s fiction—not a detective novel as has been rumored—in various coffee houses around her hometown of Edinburgh. “I will continue writing for children because that’s what I enjoy,” she said. “Not doing so has left me with the biggest emptiness in my life.” Fans know well that Rowling wrote much of the first Harry Potter book in that city’s Nicolson’s Café, which was owned by her brother-in-law. “I am very good at finding a suitable cafe,” said Rowling. “I blend into the crowd. I don’t sit in the middle of the bar staring all around me.”

And in news announced Thursday, Rowling was named to the 2008 Forbes billionaire list in the celebrity category, where she’s ranked with the likes of Steven Spielberg, Oprah Winfrey and Giorgio Armani.