I'm a bit late to the table on this one, but this is partly because I read the post and thought, well, I can't remember hearing about it first - it must have just seeped in; or alternatively that I'd heard about friends who were adopted meeting their birth families as adults, and kind of assumed that open adoption for children was just an extension of this.
But then I remembered.
In 1999 I was working in Southern California, and a mildly irritating hippy type colleague mentioned that he was heading to a different part of the state for the weekend to meet up with "his daughter's birth mother". I now remember being stopped in my tracks. At the time, I was in touch with my former foster son; I did know his father, and could see that there was some benefit in having contact, even if just so the boy could see how unreliable his father was. But I didn't really manage to link the two, not because A wasn't adopted, but because I thought of younger adoptions as being different. In fact, it is only now that I recognise the link. At the time, I am pretty sure I didn't see the point in this colleague's daughter having contact.
I've been talking recently to a couple of people (including Mr Spouse, who agrees with me) about how I find it hard that UK adopters are much less in favour of openness and contact than equivalent US adopters. Everyone says "ah, but it's different in the US, it's all relinquished babies". But it isn't, and adopters from foster care I think are more positive towards openness and contact; and there are some relinquished (or removed at birth) children in the UK, and I tend to hear the argument "they don't have a relationship, so there's no point in contact".
I hope I am able to live up to my ideals. A's dad didn't vanish or cut off contact, but mainly tended to come and see me when he wanted something. If contact is like that, I've got experience in handling it. We'll see. But I think we'll be OK.