The PlayStation Blog announced all the games that will be added to the Instant Games Collection this month. The titles in question will be Sleeping Dogs (PS3,) Knytt Underground (PS3 and Vita,) Pinball Arcade (PS3 and Vita,) Germinator (Vita) and BlazBlue: Continuum Shift EXTEND (Vita.)
Today, when the PlayStation Store updates, Sleeping Dogs will be available for free and Papo & Yo will be discounted (25% off.) The regular price of Sleeping Dogs is $49.99, so PlayStation Plus members should definitely take advantage of this promotion and download the action game as soon as they can.
Source: PlayStation Plus