I just sent the following in an email to everyone on BSA's website who had a listed email address. And I encourage everyone who believes in equality to do the same. I also recommend that you visit Scouting For All.
I really don't know who would be best to talk to about this, but these are all of the email addresses I could find on BSA's site, so I figure at least one of you will know where to send it.
I am writing to inform you that I am unpleased with the BSA's continual discrimination against homosexual people. I will therefore not be supporting the BSA in any way, and will do all that I can to discourage other people from participating in and donating time and money to your organization. And I will continue to do so until such a time comes as you finally accept homosexual people at treat them equally.
It is extremely important for young boys to feel like they have a place in the world, and I think the BSA has as one of its goals the desire to provide for boys the opportunity to fit in and to better themselves. Gay youth are extremely needy of a place to feel loved and accepted, because they are so often bullied and teased at school for being different. The BSA rejecting them is just one more reason they have to feel hurt inside and to hate themselves, to feel that they are not worthy of love and acceptance. This is one reason why your policy is so harmful and so distasteful to me.