I would have to agree that Apple really did drop the ball. However, a third party work around does exist.
My solution to this problem is to use Dropbox.com and Documents To Go. Numbers will save as an Excel Spreadsheet and Documents To Go will read it, and Dropbox will sync it. Additionally, you can setup sharing among several collegues, and everyone is sharing the same copy at the same time.
I realize that Excel file in numbers are not nearly as polished, and I do prefer the polish whenever possible, but sometimes the work just needs done.
One thing I am a little fuzzy on is whether or not icloud storage can be mounted as webdav like idisk could, that would be the ideal solution.