Bika LIMS uses the Plone Framework, Python. Can be a bit top heavy, but the gains of having a strong community assisting with, and providing most of, the heavy lifting in areas such as authorisation and security, workflow engines, content management and versioning, i18n, etc. is a tremendous bonus.
[Disclosure: Bika Open Source LIMS collective founder]
Big, no huge, LIMS LIS market out there. Many products, 500+ and growing, A fist full of FOSS, say 20. Many from academic background, and in even faster growing Bioinformatics and Biobanking. Because of those odds, forgive me the punt: please read http://www.bikalims.org/, and lend us your weight among the suits at the LIMS Circus, http://goo.gl/nK6xqv. Appreciated