I went ahead and purchase this "blank fare" for the hell of it (figured I could do a 24 hour refund if necessary). The flights show in my current reservations with a reservation number, but show:
This reservation is not ticketed. Complete this purchase now.
We will hold this reservation until midnight Thu., Jan. 10, 2013 in San Diego, CA (SAN).

When I click through, it shows a ticket price of $167.40, but I never saw this fare on United.com before this (this matches the fare I saw on ITA though). Very strange.