One annoyance however is that when you export your Numbers spreadsheet to Excel it will include a table of contents explaining how your sheets and tables were converted worksheets. While this might be helpful, it's not likely to be appreciated in a business environment.
So here is how you get Numbers to not include the table of contents when you export to an excel spreadsheet:
Simply edit your com.apple.iWork.Numbers.plist file in ~/Library/Preferences to include an additional key called "EEDropTableOfContents" and set it to TRUE.
From Terminal you can simply type
defaults write com.apple.iWork.Numbers EEDropTableOfContents
To edit it as an XML document you need to run
plutil -convert xml1 ~/Library/Preferences/com.apple.iWork.Numbers.plistthen add an entry that looks like this:
Or if you use Property List Editor included with the developer tools it will look like this: