http://www.cnn.com/2010/LIVING/12/16/holiday.birthdays/index.html?hpt=Sbin
The only people who have caused issues over my December-born child's birthday have been Christians who never seemed to get that a birthday party is a birthday party, not an early Christmas party.
Even though my youngest was born on our holiest day: Cookie Day; he's always gotten his birthday party that was just a birthday, with gifts and balloons and a cake however he wanted it (mice, cars, spaceships...).
I suppose it helps that we don't generally exchange gifts for Cookie Day, just cookies. And our decorations tend to be just the cookies, and cookies fit in well with a birthday without overwhelming the birthday.
It helps, too, that we don't celebrate Christmas.
For the longest time, my youngest thought that other people just didn't remember when his birthday was when they gave him gifts closer to the Christian Christmas. Once he was old enough to figure it out, since we weren't Christian, he just shrugged and decided it really was just more birthday presents for him. It did sort of bother him that his siblings received gifts, too, from well-meaning but clueless Christians, until he realized that they didn't get presents from those people on their birthdays. That was about the time he learned that everyone shared the same coming of age day in Japan, so he decided the gifts his siblings received were just because it was easier for those people to have a "communal" birthday for everyone in the family.
I do feel for the children whose birthdays get lost in all the Christmas frenzy.