This Quick-Tip is about an issue that some people have had with their "naked" custom domain not re-directing to the www-at-the-start version, and how to fix it using a feature in your Google Apps account.
Since Blogger released their initial fix to the custom-domain mapping problem of mid-September 2012, some people have found that it's not possible to set up the custom domain so that my-domain.xxx works as well as www.my-domain.xxx does.
There is an option for this in Blogger's Settings > Publishing area. But last night, when I set up a "subdomain" style entry for news.my-domain.xxx and directed my latest-updates blog from my-domain.blogspot.com to news.my-domain.com, found that this didn't work.
(Obviously I didn't use my-domain.com - but the principle applies.)
However today I found an approach that does seem to fix this:
1 Log in to the Google Apps domain administration account (the same one you used to set up the 2nd CNAME record - if you don't know how to get into it, some of the information here may help)
2 Go to Domain Settings > Domain Names, a
3 Sroll down to where it says: Redirect the naked domain (http://YOUR-DOMAIN.INFO) to ... (whatever it says now)
4 Click the Change Redirect link under this.
5 Make sure that www (lower case) is entered in the field.
6 Click save.
I cannot guarantee that this will always fix the problem. But it did for me just now, and I've seen a couple of other posters saying that it helped them too. So I thought it was worth sharing.