Simpson Thacher & Bartlett is announcing this morning that New York partner Lynn Neuner will become one of the two co-chairs of the firm's 250-lawyer litigation department at the turn of the year, making her the first woman to help head the practice at the elite firm. Neuner, who was inducted into the American College of Trial Lawyers earlier this year, will replace current co-chair, Paul Curnin, who is set to retire at the end of the year.