After reviewing this answer, and this one, and this one over here, I feel like I have a slightly different issue causing the same result.
Basically, when I navigate to my Careers 2.0 profile and scroll to the "writings" section, I enter the URL to my WordPress blog into the text input, click the "Get Article" button, and get the "could not retrieve URL" error message.
To verify that this wasn't an issue with HEAD redirecting or returning an error, and that it wasn't an issue with cookies, I ran the following curl command from a terminal:
$ curl -I http://www.mullist.com/2014/12/31/literally-the-first-angularjs-app-everyone-writes/
HTTP/1.1 200 OK
The server is a VPS, so I imagine there's some issue on that end. I was just wondering if anyone had more ideas on how to make my blog visible to Careers 2.0.