I (and all Punchfork users, I assume) received a notification on January 3rd, including the following:
Initially, support for Punchfork will continue, but
we will soon be retiring the Punchfork site, API and
mobile apps. We believe that a unified destination
benefits our users in the long run, and the Punchfork
team (me) will focus on contributing to Pinterest as
the premier platform for discovering and sharing new
recipes and other interests on the web.
EDIT: Gmail binned this email in "Promotions"... I wonder if that explains why some didn't see it?