When the author and former Daily News book editor Bruce Cook died last year, a number of fans posted comments here on the blog. His wife Judith Aller also came by to thank the posters. Now Aller and friends of Bruce Cook are having a celebration of his life on Saturday at the Dutton's Books in the Valley, 5146 Laurel Canyon Blvd., Valley Village. It's from 6 to 9 p.m. and was mentioned on the KCRW air this week by David Kipen in his Overbooked spot. Cook's novel, Young Will: The Confessions of William Shakespeare, has recently been published. For those who don't know, Cook wrote The Beat Generation, Listen to the Blues and Dalton Trumbo as well as ten Sir John Fielding historical mysteries under the pseudonym Bruce Alexander and four Chico Cervantes detective mysteries. He died last year at age 71. * Correction: A final Sir John mystery, The Rules of Engagement, will be released by Putnam in the spring. It was unfinished when Cook died, but Aller and John Shannon helped complete it.