Ten years ago, resumes used to include your hobbies and interests so that employers would know a bit more about you, beside your career and education history. Nowadays, the employment market being so competitive, rules have changed. Because employers receive hundreds of resumes, they don't have time to read the fluff and will only focus on what you will bring to their company. As a result, they won't care if you play in an amateur softball team on weekends.
However if this hobby might be somewhat related to the job you are applying to, you should include it in your resume. For example, if you are applying to a manager position and, on your free time, you are volunteering for the red cross, managing your fellow volunteers, it is recommended to include it.
Another case is if you are fresh out of college and have no experience. In this case, it will be a way to fill your resume. Of course you should put some stuff that will bring something positive about you not things like you' re playing video games all day.
- Gail Esparan