Must code I contribute to Plone be GPL?
In order to become a contributor to Plone, you must sign the Plone contributor agreement, through which you assign copyright in your code to the Plone Foundation. All Plone Foundation-owned code is released under the GPL, except for selective libraries released under the BSD license as described above. So, yes, if you checkin a new package to the core Plone code repository, you must check it in with a GPL license. You, as the code author, do not get to choose which license under which to release the code.
