Question for Joel: How can professionals make time to moonlight without jeopardizing their day job?

When I think back on my own career, moonlighting or volunteering at a non-profit would have been next to impossible because my "day job" demanded so much of me. Given that companies are trying to do more with fewer people, how can professionals (salary based workers) moonlight or volunteer at a non-profit without jeopardizing their "day job"?