I would be interested in this too. I read something about packaging in my PPA welcome packet and it made a lot of business sense.
Right now I just started using the Millers boutique packaging, but it would be nice to have other options. I'm also considering just having some cheapy stickers made of a photo from the clients session to seal the package and then just throw in the rest of the sheet for free. You can get them through cheap consumer labs for about $4-$5.
Does that seem like a nice personalization or cheesy? I haven't done it yet, so I'm not sure of the quality of them.