While it might sound strange for a newspaper to get into selling ebooks, this isn't the Trib's first such effort. They have been selling their own ebooks (and giving them away to digitalPlus subscribers) for a while now, so this latest move comes as only a small surprise.
The bigger surprise today is how the Trib managed to keep it so quiet; it's been operational for at least a month but I only learned of it when they announced it to their digitalPlus subscribers last night (thanks, Matt!).
But what's more important than the surprise is the disappointment. This ebookstore stocks over a million titles which can be read by the integrated Android and iOS apps, but the ebooks unfortunately cannot be transferred to ebook readers (or so says the FAQ). That is a startling difference from the other two ebook sites operated in The Chicago Tribune's name; one site did not use DRM, while the other used Adobe DE DRM and enabled users to transfer their ebook purchases to their ereaders.
Like any ebookstore TribBooks offers sales and special deals, but it also has deals that are exclusively available to The Chicago Tribune digitalPlus and Printers Row Journal subscribers. These subscribers can log in to TribBooks with their existing subscriber account and take advantage.
By offering special deals to Trib subscribers, the newspaper both adds value to the newspaper subscriptions (which is still one the newspaper's main sources of revenue) and encourages those subscribers to come back and buy more ebooks later. This is a classic loss leader strategy adapted to serving two goals instead of just the one.
On a related note, this is the second time I have reported on a newspaper launching an ebookstore. In December 2013 Bild.de launched an ebookstore on the Tolino platform. I can't tell you how much work they are putting into cross-promotion but it would be smart for them to do so.