A plugin is now available (in beta) for users to synchronize Calendar and Contact information between vtiger CRM and other applications which support SyncML (ex: GMail, Zimbra)
To Install, just download the file below, and copye the syncml folder on your root vtiger directory, and be sure your webserver can write on file syncml.log thats all.
http://www.abonlinesolutions.eu/publications/telechargements.html
This plugin has been contributed by one of our community members, Aissa from ABOnline solutions (abonlinesolutions.com) , with assistnace from Simon, Sylvain and Nini from “La junior entreprise AEI (junior-aei.com)