Available from Confluence 5.9
You can search for pages with workflows applied to them, filtering by the different available workflows fields. In case you are looking for a way to create workflows reports, consult the Reporting section.
In the Confluence general search screen, you can add filters to perform an advanced search, by adding additional filters, like the workflow state or expiry among others.
Confluence provides some macros that support CQL filters, like the Content by label macro or the Page properties report macro. Add filters to display pages with workflows fields, like the workflow state (e.g., Waiting or Ready).