I also strongly support this. This would be an idea situation and would convince many potential users of the altruistic goals of Mendeley. Many users are very much tired of proprietary formats and monopolies controlling our information. If Mendeley offers good value for its more advanced paid services, I'd also be happy to join

I also strongly support the movement towards open source software and hope to see a type of partnership between Zotero and Mendeley. Zotero is a great reference manager and has a loyal following precisely because it is open source.