Currently, you can view all of the "Workflow Memberships" for a given Contact simply by viewing the Contact itself and viewing the right-hand side menu. However, this does not exist for Company and Deal objects and would be super beneficial if it did.
Additionally, when viewing your Workflows from the "Workflows" page, there are metrics for "Total" and "Active" enrollment, BUT there is no easy way of viewing WHO (or what objects) are actually enrolled in those Workflows. The closest you can get to these is by clicking an individual Workflow, viewing the "History", and then applying filters or searching through the "Select a [object]" dropdown - but even this doesn't give you a definitive anwer because from what I can tell this is just a list of all objects (Contacts, Companies, Deals) that had any association with the Workflow, even if it was just temporary or they have since be un-enrolled.
There is no indicator on a Company and Deal telling us what Workflow(s) that object belongs to
There is no way to see in an aggregate view which objects are actively enrolled in Workflows
Workflows are extremley useful but as they currently stand are an absolute nightmare to manage/maintain/track/review.