Hi Barry,
Yes, you can set tooltips for the entire Gauge report control or for individual Gauge elements. This can be achieved from the Action tab in the gauge editors.
For example to set a tooltip for the gauge pointers - from the Gauge Editor go to the Pointers tab, select the pointer you want (you may need to add one) and from the Data tab set the pointer value. Then, from the Action tab you need to select one of the alternatives offered by Reporting Services (Jump to report, Jump to bookmark or Jump to URL) and set the Label for the gauge pointer.
Hopefully this helps. Let us know if you have any questions or comments.