Microsoft has been granted a patent for contextual ebook ads, according to Engadget. This means that ebooks could now have advertisements while users are reading. There is speculation as to how this might work, in that companies can try to sell ads in certain genres. Sports companies could find a market to advertise to in sports-related books, etc.
Time will tell if advertisements in ebooks will turn off ebook readers and drive customers toward print editions. Even though Microsoft has this patent the company will be inserting ads in between every page. Currently, Microsoft does not have a dedicated reading app.