Do you know the HOBOS project at the University of Wuerzburg?
http://www.hobos.de/en/students/hobos-data/beehive.html
http://www.hobos.de/en/students/hobos-live/chart.html
For commercial hive scales have a look at http://hackerbee.com/2012/10/02/meeting-about-bee-hive-monitoring/#comment-21 there is an overviews about existing solutions - most in Germany. Or have a look at http://arduino.cc/forum/index.php/topic,113534.0.html