Take Two has renewed trademark registrations for Agent, which says to us that they still intend to release the Rockstar North title.
The game was originally announced as 'in development' back in July 2007 as a PS3 exclusive, however, no other details (including the project's title) were confirmed.
At an E3 press conference in 2009, more details (including the game title) were announced alongside this quote: "Agent
takes players on a paranoid journey into the world of counter-intelligence, espionage and political assassinations during the height of the Cold War at the end of the 1970s."
All very interesting stuff! Check back for more info as it unfolds.