I'm certainly not an expert in California law, but I would point out that currently under PIPEDA, and under the principles at the end, there's a general right to withdraw consent for the use of any personal information, subject to contractual or legal restrictions. I would think that in a situation where someone had posted something themselves and wanted it removed, and there was no other valid contractual or legal reason an organization should keep or post it, in many cases PIPEDA would now require that it be removed.
I think a lot of social networks actually do operate this way. If you post something to a lot of social networks, you can remove it after you've posted it. It doesn't change the fact that people have seen it, and in some cases might not change the fact that others have copied it and distributed it in other ways, but you can pull it off the actual network it's on.