I have seen a few references to and snippets from to a new study "Bridging the Divide: Openness in Adoption and Post-adoption Psychosocial Adjustment among Birth and Adoptive Parents" Journal of Family Psychology, (possibly not published yet) 2008
If anyone has access to the full study, I would be interested in reading it and it looks like it would be of interest to most of our members.
I was able to find the study here: here at the Pittsburgh Mother & Child Project page. You can download the study right here as a .pdf file.