Example: Applications on workspace 1 would be sorted to the left and applications on workspace 2 would sort to the right. This does not mean that if you have so few applications that the task list is not full, that applications on workspace 1 should appear on the left side of the task list and applications on workspace 2 should appear on the right side of the task list. This should only effect the sorting of the applications in the task list.
I assume you mean the tasklist, because the window list is already sorted (with separators) by workspace. Anyway, the 4.8 panel will provide different sort options; default is by workspace, group name and window title.
*** Bug 6869 has been marked as a duplicate of this bug. ***