Although it may seem self-evident, the LiveSite Developer's Guide (Release 2.2) tells you that to reference the selected value of a SelectSingle Datum, you simply append:
/Option[Selected='true']/Value
to the xpath of the element you need.
If you don't recognise this typo comparitive to usual xpath referencing, the correct way to reference the selected value is actually:
/Option[
@Selected='true']/Value
Small tip, but useful if you are new to xpath referencing and semi-relying on the iwov guide to lend you a hand!!!!