I don't think a recruiter will be impressed by putting something like this on your resume, but I don't think it could hurt either. Most recruiters don't pay attention to these things, they screen you based on pre-set criteria like school name, major, GPA, impressive extracurriculars(i.e. played for univ football team), work experience. The poker thing might help you in an actual interview with a trader when he starts asking you about taking risks etc. I believe this helped me when I landed a job at a hedge fund(not there anymore).

As an aside, I think I listed "poker" as one of my hobbies toward the end of my resume. Maybe I even mentioned it in my cover letter for some trading jobs. Consequently, I had heard the Susq guys were pretty big on poker, and I was offered an interview there but never took it. Don't know if they cared about the poker thing or not.