The episode shows characters from the show in both live action and as pictured in The Sims 3 world in fantasy sequences. The CW web site also launched a Sims 3 page where you can get Sims 3/One Tree Hill wallpapers and screensavers. This kind of massive promotion is not unknown for the show. In fact Entertainment Weekly recently stated that One Tree Hill has more product placement than any other scripted show.
Gallery: The Sims 3 Screenshots