Grok is a project to give sane, easy to use, API to Zope 3 systems. It exists as standalone, but Plone compatible port five.grok is available for Plone 3.3 and onwards.
Benefits over using pure Zope 3 APIs
Grok will automatically scan all .py files in your product and run registration code in them. This way you can use Python decorators and magical classes to perform tasks which before needed to have hand written registration code.
More info