The one page rules may no longer apply—but most recruiters will lose interests after two pages.
In the today's digital age, electronic resumes are more common and because of that it's no longer important to limit your resume to one page. A two page resume is far better than a one page resume with margins outside the printing area in small-sized font. That being said, the average hiring manager spends about 10-30 seconds in reviewing each resume; so be as concise as possible. One exception--longer resumes are common in IT jobs.