I'm helping collect the design considerations for letting users see the version number of an item that was published to each Target Type in the Content Manager Explorer.

So far we've covered:

• Show in GUI, per item. We can show this information upon request. Maybe we can add it to Where Used helps, which has publication targets instead of target types but no version numbers (are those stored?).
• Non-editable data. We'll store information in Application Data rather than metadata (authors shouldn't change). We wouldn't content port this since it's specific to a given CMS environment (in DTAP).
• Sync with Rollbacks. We must handle rollbacks, especially with delete, either by adjusting values or storing entries (similar to Chris Summers' "Save & Comment" PowerTools extension)
• Automation? I'm not partial to where the automation happens, but Event System seems a better fit than storing this is Content Delivery.

I'm just not sure on scheduled publishing, especially in done in phases. I think authors would want the version of the item as it was rendered, but we might also need to handle failed publishing transactions.

Am I missing any scenarios or do you have any other recommendations for letting users see which version of an item was published where?