It is, I think, a rule of the internets that if you do something well and openly, that someone will sue you. In this case, it’s the makers of Endnote suing Zotero for having the temerity to help users access their information.
The complaint states, “Dr. Daniel J. Cohen, Associate Professor, Department of History and Art History, and the director of GMU’s Center for History and New media, developed Zotero, which is a freely distributable, open-source software based research tool that allows users to gather, organize and analyze sources, including citations, and freely share the results with others.” (my emphasis)
That’s certainly grounds for complaint! Curse you, Dan Cohen, for your commitment to open software, free intellectual exchange, and fruitful research!