http://www.bbc.co.uk/whatson/tickets/shows/parsons.shtml
Parsons and Naylor's Pull Out Sections are back for a new series soon. They have called for open submissions in the past few series so I expect it's the same for this one.
It's topical stuff so they accept items for the whole week in the run-up to the show but I'd recommend listening to a couple of shows first as the format is quite unusual and specific.
Best of luck
Dan