April 2010..
5% down up to 417,000 and 10% down over $417,000
is possible again for conventional Fannie/Freddie loans in CA.

You do need a good middle credit score, I think it is at least 720 for 10% down and 760 for 5% down.
Mortgage insurance is extra.
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For FHA loans the up front funding fee has been increased to 2.25% of the loan amount. On a $400K loan this is $9000.00 (wasted)

If credit score does not qualify for Fannie/Freddie then FHA is the only option with a low down payment.