EA has made Katy Perry the spokesperson for The Sims franchise, and will be co-designing a set of DLC with the singer for many Sims games, including clothing, accessories and furniture and other items.
Launching the new partnership, EA plans to release a new "Collector's Edition" of The Sims 3 Showtime featuring new content, which will be released this March. Showtime, a Sims 3 expansion pack, focuses your Sims' story on becoming a musician. The Collector's Edition includes a new "ultimate stage" venue, along with Katy Perry items like a guitar, clothing and a hairstyle.
If you are a Sims fan but not really into Katy Perry, there will be a "limited edition" version of the "collector's edition" without the singer's virtual gear.
EA didn't specify which Sims titles would be getting the new pop star-inspired content, but I'd say it's safe to assume that The Sims 3 and its expansions will have access.