I agree Renegade... PHA sororities (at least mine) stressed the same thing- lifelong commitment. But I think it's common for people to say "I was in XYZ sorority/fraternity." I am a Sigma Kappa Alumna. When I lived in Europe, I held a leadership position (VP of Programming) with the European Alumnae Chapter, but it was brief as I left Europe earlier than expected. I didn't have enough room to mention it with all of my other extra-curriculars, but two of my LORs were from sisters who are Majors in the AF. They mentioned that we became close as a result of my involvement with the Alumnae Chapter. I don't know my results yet, nor will I ever be sure if SK contributed positively or negatively to my application, but I'm proud of being Greek!!!
Just as a side note, Greeks do a ton of community service (at least all the chapters I know). Lots of people fail to realize that, but that kind of commitment to the community should definitely be a plus.