CAMBRIDGE, MASS. (AP) — Facebook creator Mark Zuckerberg has returned to Harvard University to enlist new talent for his social networking site.It's the 27-year-old CEO's first official visit to the Ivy League school since he left in 2004. Relations between the two have sometimes been prickly. He met with Harvard students and officials on Monday after a recruiting visit to the Massachusetts Institute of Technology earlier in the day.At Harvard, hundreds of students lined up to watch him briefly speak with reporters. Zuckerberg said he's back because "there's a lot of really smart people here."Harvard freshman Aaron Perez, an 18-year-old from Poughkeepsie, N.Y., says Zuckerberg gives hope to students wondering if they'll be able to find a job. He says Zuckerberg's invention changed the world and is one of the reasons he chose to study computer science.