Check if Workbench Content Has Published Revision
I'm assuming this question is about D7 ...

Step 1 - Flag published revisions

Use the Flag module to flag Workbench content whenever a published revision gets created. The flag you'd want to use is a global flag. To actually flag such content, use the Rules module.

Step 2 - Check if flagged

Adapt your existing Rule(s) (for advanced Workbench notifications) to take into account if your content has yes or no been flagged. To do so, you have a choice:


Split your current Rules Action (for those notifications) in 2 Rules Components (in which you can use Rules Condition to check the flag).
Use the Conditional Rules module so that you can include the required Rules Condition(s), to check the status of the flag, within the Rules Actions of your existing rule.