While not exclusively a Gnu-Linux product (runs on LAMP and WAMP stacks), the selection of OpenEMR by the Peace Corps for its worldwide EMR needs, lends a powerful measure of legitimacy and value to the use of open source EMRs in general and OpenEMR specifically. .
http://www.govhealthit.com/news/peace-corps-plans-ehr-system-2013 .
OpenEMR continues to grow its active developer community incorporating state of the art capacity including 5010 standards, Android apps, etc. .
http://www.open-emr.org/ .
Jack Cahn MD
OEMR.org Board