I’m not sure what The Sims Carnival is anymore. I have always thought it was a series of games, but now it is an online community built around game-creation and sharing. Anyways, you can sign up for a free closed beta test at TheSimsCarnival.com. The Sims Carnival will allow you to “create games from scratch”, “build a community around your own game creations”, embed your favourites in a blog or social networking site, and of course swap things with friends.
Sign up to beta test in The Sims Carnival