I have noticed that Play! Framework encompasses persistence strategy (like JPA etc...)
Why would a web framework care about persistence ?!
Indeed, this would be the job of the server-sides components (like EJB etc...), wouldn't this?
Otherwise, client would be too coupled with server's business logic.
UPDATE: One answer would be : it's more likely used for simple application including itself the whole business logics. However, for large applications with well-designed layers(services, domain, DAO's etc..), persistence is not recommended within web client layer since there would be several different web(or not) clients.