Take this info with a grain of salt, but the answer is yes, according this thread on Flyertalk.
According to a 1K agent (the ultimate authority…), United will begin to test one-way bookings online starting 01 February. If these awards are going to be bookable online, it may be they are for United metal only, at least for now.
As we have discussed in prior podcasts, there are advantages and disadvantages to one-way awards. My concern is that switching to a one-way award system like American Airlines will spell the end of free stopovers on roundtrips. As you will read about in my upcoming trip report, I always take advantage of the free stopover on award tickets–essentially you get to fly to another city for only a few dollars in taxes.
American eliminated the free stopover on roundtrip awards when they introduced one-way awards. I hope United will lead rather than follow and not take away the stopover perk.
I will post more details as they become available.