I have an app hosted on Google Appengine and I'm using my own domain. Even after editing the DNS zone (about 5 days ago) the naked domain is still not redirected to the www.
Here are the settings in Registro.br.
Nome Tipo Dados example.com.br A 220.127.116.11 example.com.br A 18.104.22.168 example.com.br A 22.214.171.124 example.com.br A 126.96.36.199 www.example.com.br CNAME ghs.googlehosted.com
Here are the settings in Google Apps:
Primary Domain Redirect the naked domain http://example.com.br to http://www.example.com.br
I added the following IPv6 values and now the naked domain redirect works:
Nome Tipo Dados example.com.br AAAA 2001:4860:4802:32:0:0:0:15 example.com.br AAAA 2001:4860:4802:34:0:0:0:15 example.com.br AAAA 2001:4860:4802:36:0:0:0:15 example.com.br AAAA 2001:4860:4802:38:0:0:0:15
I don't know if it's because the BR record takes a long time to update the DNS values or if the IPv6 values were really needed.
IPv6 values were found in this Google Apps Support article .