Two things I would like to see. First is a way to run all filters on the inbox. I can now create a filter on a message, but it would appear that it only works on new messages. Messages already in the inbox need to be moved manually.
Second, with the move towards web based and portable, it would be nice if Zimba Desktop could be run from a USB drive as a portable app. I currently run Thunderbird as a portable app and it is very convient. I think that would be the ultimate combination for Zimbra. Online and portable app.