It turns out to be legit. But it feels so scammy. This is not the way to convince technical users (people comfortable updating A Records) to make significant changes with regard to your site.
Seems legit... but I don't see anything on the blog so I think I'll wait until I see something there. It does seem very phishy to me.<p>dig custom.posterous.com<p>;; QUESTION SECTION:<p>;custom.posterous.com. IN A<p>;; ANSWER SECTION:<p>custom.posterous.com. 3600 IN A 184.106.20.102
It's legit, we're switching our servers from one location to another and this will prevent an extra hop and possible latency for sites using custom domains.