For fields like story points it would be useful to have a culmulative field that summed them down the board

We often use JIRA to help us with release planning using Greenhopper.

We have a list of of issues each with a stories point assigned. We would like to be able to quickly see the culmulative total down the list - so as we reorder things we can see when future releases are likely to fall.

e.g.
JIRA, Description, Points, Culm Points
JIRA-1234, BLAH , 10, 10
JIRA-1234, BLAH , 10, 20
JIRA-1234, BLAH , 10, 30

This should ideally be possible in both the green hopper boards and the issue navigator (to make exporting to excel easy).