Dean's List is a method that positively reinforces academic achievement for students. Each college or university sets its' own academic standards-- it's a local policy. Dean's List gives students something academically to shoot for. This is good in my mind. Generally it is GPA based.
Apparently, Smith has recently modified its' criteria for achieving Dean's List recognition. The faculty may have upped the standard somewhat-- I recall minutes to this effect from a major faculty academic committee. I noticed this nosing around on the Smith web site.