i'm a med1 here at OSU, and from what i can tell, there's only a small percentage of students that match in cali. it's probably b/c us out-of-staters are more likely to apply to cali vs. our in-state students. the in-state students for the most part match around ohio and the midwest region, where they prefer to stay. here's a link of OSU matches for the past few years:
<a href="http://academic.med.ohio-state.edu/resmatch/" target="_blank">http://academic.med.ohio-state.edu/resmatch/</a>
from the matchlist, you can see that it's definitely possible to match in cali. unfortunately i can't give you the percentage of cali students here at OSU that actually match back to cali for their residency. although i'm sure i can find out if i ask around. hope this helps. good luck
harry