A brief spin through Google turned up a couple hundred similar listings from HarperAudio. They have all since been taken down, but the ones in the Google cache looked like this:
When I queried Kobo on this topic, they neither confirmed or denied the implications of the listings. Instead, Rene said that "This seems to be an error in the metadata provided in this case." That is a curious answer, so I double checked the ISBNs. They match up with the respective HC audiobook titles.
Kobo isn't currently selling audiobooks, and they haven't announced plans along those lines, so it's not clear what the new listings mean. They could have been a technical error, but they could also have inadvertently leaked Kobo's future plans.
Remember, I broke the news on Kindle Unlimited after members of KBoards noticed that several pages for that section had been posted on the Amazon website. That could well be what is happening here.
Kobo could be quietly signing publishers with the goal of launching an audiobook section, or they might be taking the same path as B&N, which slapped the Nook brand on an audiobook platform developed by Findaway World earlier this month. Findaway offers a catalog of 50,000 titles. That's far smaller than the 150,000 carried in Audible but it could still be enough to attract customers.
On the other hand, this could just be a technical error. We'll just have to wait and see.
I for one hope that it is true because Amazon could really use the competition in this market. More retailers means more competition means lower prices, and that's good for consumers.
If Kobo does get into audiobooks, they will be competing with Audible, iTunes, Nook, Downpour.com, Audiobooks.com, and Random House Audio, which distributes titles and also sells direct. Amazon's Audible is believed to dominate the market.