Can you let us know what we need to advise users about how to CNAME their top level domain to their multisite blog? CNAMES, as I understand them, are only meant to be used in conjunction with subdomains. In other words, you can't CNAME topleveldomain.com. But you can CNAME subdomain.topleveldomain.com.
So what if a user wants to map mydomain.com to their multisite blog? Sure, they can modify the CNAME for http://www.topleveldomain.com. But what about traffic without the www? Someone suggested forwarding that traffic to the www variant of the domain, which is then mapped to the multisite blog. But that seems like a lot of setup that users will find confusing, not to mention a lot of redirecting.
What should we tell users about setting up a CNAME for their TLD?