REST = Representational STATE Transfer. Client and server exchange the state of a resource. So basically it's kept on the server and updated (/created/deleted) by the client.
REST isn't awkward at all for workflow applications, however you may define that. The most difficult part when designing REST applications is designing the representations and most of all the resources. A resource isn't merely an entity from the database.
As @NeilMcGuigan has mentioned, the RestBucks sample application deals with workflows. There's a video on the SpringSourceDev Channel on YouTube, where Oliver Gierke presents the application.