It was an interesting experience browsing through Zimbra mail. I was wondering , if there is a plan to add "Task" functionality in Zimbra.
Also, I would like to know how I can contribute to Zimbra effort, being an content management consultant with multiple years of user interaction experience.
Yes Task/Todo support is on the roadmap. As for helping you can report bugs or issues you find after installing our software. Soon we'll have a public bug database so this will be easier. Also take look at our Top Projects page. This has some ideas about things we'd like help on.