Is there a way to forward Growl notifications to Notification Centre?

Sure is.

Hiss is an app that takes the place of Growl to catch Growl notifications and reroute them to the Notification Center.

One limitation of Hiss, however, is it displays all notifications as coming from Growl, rather than the application that actually generated them.

Since version 2.0, Growl supports "bubbling" notifications to the Notification Center out of the box. You can find the setting for this in the General tab of Growl's preferences.

It does come with the same limitations as Hiss though, all notifications appear to be coming from Growl and not the originating app, and clicking them does not appear to launch the expected actions.