From the CSU website dated Oct. 1,2009:
California State University Opens Priority Application Today for Fall 2010 | CSU | Public Affairs
"High school seniors meeting the CSU eligibility criteria receive priority admission at the CSU campus in their local service area (with some exceptions including San Diego and the coastal region) and students are encouraged to apply to their local campus to ensure admission to a CSU for fall."
I'm pretty sure SLO is considered "the coastal region" and is an exception to the local service area priority admission policy.