Seems to me that although it isn't a "scam", there doesn't seem to be any real benefit from joining. I don't know many recruiters who would even give it a second look on a resume and it would be no different if you said you had a 3.5 GPA then if you said that you were a member of this. They actually say there is no requirement to do anything, so really what would the point be.
Perhaps if your school has an active chapter there is something you can get out of it..but it doesn't seem like it.
Just look at their financials. as of 2011 they had only 1.3 million in assets and gave out 353,000. I'm not criticizing the percentages, just the numbers. This indicates to me that they don't have any real corporate backing if that's all they have.
Most colleges have honors programs you can get just as much out of.. probably more.
Really just look at it this way...if you have a GPA that is 3.5, a recruiter will know that easily...you don't need this organization to verify that so it is meaningless on a resume.