After visiting a number of site with grid-like UIs, I've found that the UI is most effective if all fields that can be sorted have a sort icon next to them.
Fields that can be sorted have a split diamond icon.
The current sort field has either the top half of the diamond (for sort descending) or the bottom half (for sort ascending).
|Transition||Time In Source Status||Execution Times||Last Executer||Last Execution Date|
|33d 12m||1||Howard M. Lewis Ship||24/Jun/07 18:05|
|Workflow||Default workflow, editable Closed status [ 12567253 ]||jira [ 12589948 ]|
|Workflow||jira [ 12404593 ]||Default workflow, editable Closed status [ 12567253 ]|
|Resolution||Fixed [ 1 ]|
|Assignee||Howard M. Lewis Ship [ hlship ]|
|Status||Open [ 1 ]||Closed [ 6 ]|
|Fix Version/s||5.0.5 [ 12312477 ]|
|Field||Original Value||New Value|
|Issue Type||Bug [ 1 ]||Improvement [ 4 ]|