I don't think there is a way of showing when an idea was shipped -- seems like an obvious thing to show.
This can be achieved through the use of custom fields. You can use a Date custom field to enter the date in which the idea was shipped.
If the idea was linked to a feature, you can also click through to the feature to see the release date associated with the feature. However, there may be other circumstances where an idea might not have been linked to a feature -- in this case, the custom field would also support this scenario.