To install it, first add the appropriate repository in Cydia: http://iphonedelivery.advinux.fr/cydia

You should then see iPhoneDelivery appear in the list of packages. Once the package is installed, two new options will appear in Preferences > Messages:

iPhone Delivery

The first one activates return receipts, while the second allows you to request display of a popup when the receipt arrives.

Warning: some operators charge for delivery reports, so check if that is the case with your operator before you activate this option!

Tested revision: 0.1.2
Source: Cydia / hack-tool (iPhoneDelivery repository)
Price: free