Animation
Infinite Sims uploaded a motion render video called “Death by Flies” which demonstrates what the animation and movement will be like in The Sims 3. The animation is clearly much smoother and much less choppy. Although there are rumors that this was an April fools joke I personally think it is real and will keep it on here until it is confirmed otherwise.
The Mysterious Painting
This painting was included in The Sims 2: FreeTime. If you look closely you can see that it is a very advanced looking neighbourhood. We are assuming this is what the neighbourhoods in The Sims 3 will look like.
Note the house under construction, this suggests that the neighbourhood will be one large seamless world which our sims can travel through in real time without loading screens.
Also if you look really closely you can see a car with a plumbob floating on it!

The Video Game
When the player installs The Sims 2: FreeTime, everytime a new family is created a Sim version of The Sims Executive Producer, Rod Humble arrives on the lot. He drops of a parcel wrapped with a ribbon. When it is opened it reveals a computer with a llama on the side in traditional sims style. The sim then has an option of playing The Sims 3.

A high quality screenshot. Showing the new furniture placed at an angle!