Well. After testing the spreadsheet capabilities with Zimbra Documents I have found that ONLY Internet Explorer works correctly with this feature. I have filed a bug but God knows when that will be fixed. When I say properly, I mean work in the same fashion that openoffice and ms office (excel) would work. Editing and entering data into cells requires a double click in every single browser OTHER THAN Internet Explorer. In Internet Explorer it is like using excel. In firefox (tried it in 4 different OSes) the UI fails to properly edit the spreadsheets.
The most discouraging part is that EVEN ZDESKTOP doesn't work! If you try to edit a Document with a spreadsheet in ZDesktop (tried OSX version) then you might as well use Firefox with the web client because it is the same thing. Someone in #zimbra@freenode told me that it is a problem with the UI. Still though. Doesn't work in Firefox? Doesn't work in ZDesktop? But works in IE? Isn't Zimbra supposed to be challenging MS for a collaboration share? Yet the only browser you can edit a spreadsheet in Zimbra is IE?

I'm sorry but I just don't know whether to be shocked or amused.
This is holding up our migration. We were trying to eliminate as many apps as possible and replace old MS boxes with low powered Linux based boxes for users on the network. The goal was to use only a minimal Debian install and Firefox to see whether the entire office can use just the web browser client as its main source of collaboration instead of using 10 different applications. If anybody has any ideas on how to fix this other than: "Use Openoffice" I would appreciate it.
Zimbra has the potential to be place into an embedded style system but things like this make office managers iffy. I understand that there are many other things that are being worked on but if the point of the office application was to draw a cooperate crowd then I personally think the Zimbra developers should seriously take a second look at their Document abilities. The software has the potential to save companies thousands of dollars on MS Licenses while gaining tons of customers if it can finally be put into a proof of concept where a company is willing to use it as a replacement to everything and show other companies how they did it.
All I can do is report the bugs and hope they get fixed.
Software Tried:
Operating Systems: Nexenta (Opensolaris), Windows, OSX, Linux (Debian)
Browsers: Chrome, Chromium, Firefox, Iceweasel, Opera (Total Failure but not suprising), Epiphany, Safari, Internet Explorer 7
Only IE7 worked properly. The spreadsheet felt like a spreadsheet.