Well kinda because there was a road sign of it for Coney Island and there was a big picture of it in Agent J's room, but sadly there is no real talking pug in Men in Black 3.
Yes there will be, if you check on wikipedia.com for Men In Black 3.
Will Smith and Tommy Lee Jones have agreed to sign a contract.
Its says it comes out in 2011.
men in black 3 will generally revolve around time travel and how agent j must travel through time to prevent the future from being taken over by a demonic biker(jemaine clement).