Windows 8 is expected to provide taskbar on secondary Monitor. Whether Microsoft provides extra taskbar on Windows 8 or not will be uncovered soon. However an extra 3rd party Multi Monitor Software can provide you whatever microsoft does not provides. Yes Windows 7 provides many useful ways to control dual or multiple monitors with control panel, still there are many things that a Multi Monitor Software can provide and make using of Multiple Monitors on any version of Windows really easy and fun to have.
Having different wallpapers on dual monitors is something that Microsoft does not provides on Windows 7 and there are chances that Microsoft will continue not to provide way to set different background on different Monitors. In case you are using only 2 Monitors connected to your Windows 7 and plan to use same number of monitors on Windows 8, the Dual Monitor Software can be of help.
Shortcut Keys, Desktop Shortcuts, System Tray Menu in comprehensive software with all Monitor control features can be really of use. You can even submit a feature request to the provider and the software provider can try to implement the feature for your version of Windows. Even if an extra taskbar is provided in Windows 8, an additional Multi Monitor Software can still be of use & worth giving a try.