I am also a concerned adult, and I hope SL does address our concerns. Here are mine.
1. I'd like to know if I'm communicating with someone who is underage. That brings up two problems -
a. I'd like to see their age, but don't want my age shown.
b.. If their age is shown, I'm sure there are those in SL (as there are pretty much anywhere) who would take advantage, abuse or otherwise choose to harm or exploit them, therefore it seems that for their safety, their age should not be shown.
2. I like the freedom of being in a place where children aren't allowed. SL has already cracked down on art that displays nudity, what is our creative world going to become when we are required to create and behave in a way that is acceptable for children?
I would like for everyone to have the chance to experience Second Life, but my reaction at this time is that mixing underage people with adults may bring in more people, but as a consequence of those people being underage it may cause just as many to seek out a new world where adults can create and behave as they like without being concerned for how they will affect children.
On first look, this doesn't seem to be such a good idea for the children or the adults.
And I guess I can express my concerns all I want, doesn't seem to me it will have much affect since they're letting children in.