Mac Rumors: Apple Mac Rumors and News You Care About eWeek first reported on an interesting breakdown of Apple’s retail marketshare. According to numbers from the NPD Group, Apple’s Q1 2008 retail (brick and mortar) reached 14%. Note that by limiting it to retail, they’ve excluded online sales and institutional/enterprise sales. !http://images.macrumors.com/article/2008/05/19/234608-macq108_400.jpg! Chart from eWeek…