Tesco, who will always be remembered as the company who sold a stripper pole for 6-year-olds, had no real presence in the ebook market even though they had an ebookstore and sold several different ereaders, including the Kindle.
Mobcast was one of the lesser options for ebookstores, and according to the press release it carries a mere 130 thousand titles. In spite of that fact Mobcast has had some success in their niche, having provided ebookstores for telecoms like Nokia (in several countries), T-Mobile, and Orange. They also ran the WHSmith ebookstore - right up until that British bookseller became Kobo's local partner in the UK.
And now Mobcast belongs to Tesco. This is just the latest move by the retail giant, which has been gobbling up content distributors for the past year. They've acquired Blinkbox to offer streaming video, We7 to offer streaming music and Mobcast to sell ebooks. I wonder if Tesco is looking at Amazon's content empire in the UK and wishing they could match it? Tesco isn't there yet but they are catching up fast.
Mobcast has also been running their own ebookstore ever since they lost WHSmith as a partner. Uncuva, a site which has twice won the title for "most likely to be named after a disease", has reading apps for Android and iOS. There's no hint of plans for an ereader, but in this day and age that's less of downside than some might expect.