I don’t know how I miss this one! Familysearch.org now has the San Francisco, California Passenger Lists 1893-1953 Collection. The collection is indexed and linked to the original ship manifests.
Be aware that the index is not complete. I did a few surname searches and found that it covers roughly 1916-1953 at this time.
The collection includes ship manifests coming from Hawaii to San Francisco. This should be very helpful for Hawaiian researchers who are looking for relatives who left Hawaii (even on vacation). You may also find those already settled in California returning from vacations to Hawaii.
Well worth keeping an eye on this one!