I want to know this too!! I'm already seeking all the pictures/information I can on it - I just love the slouchy look of it with the shoulder strap. I read somewhere (I think on tPF) that the price is definitely more than the Lady Dior - maybe someone could confirm/deny this?
From Dior Mag, not a lot of information but a lovely read:
Those who're already familiar with it can consider themselves among the ultra privileged. The reason being that the Diorissimo bag, the house's newest offspring, entered the world beneath a veil of exclusivity. Its immutably-shaped personality is immune to compromise and, for its launch, it preferred the route of intimate introductions: when one is called Diorissimo, it's not up to one to make the first move. It's not due to shyness that it remained hidden for its first few months of existence. No display in the stores, not until early March; a few clients were the only ones lucky enough to gain, secretly, first access to this inimitable new item.
"Hello, my name is Diorissimo, please come and meet me in private", the bag suggested. It has been necessary, putting it bluntly, to almost be a family member in order to be among the happy few who have experienced this special opportunity because, let's face it, Diorissimo is a luxury intended for the initiated. "A bag for daily use should be simple and elegant," Christian Dior declared. Producing one necessitates the highest levels of savoir-faire. Little hammer taps, absorbed by the softness of the leather, are performed to even out the joins between the various parts. The leather pieces are smoothed down then colored by hand for perfect tonal uniformity. A saddle stitcher assembles the skins together with the utmost precision. The charms are galvanized in very special baths. And inside each bag, concealed from prying eyes, "Christian Dior Paris" is discreetly hot-stamped. In lilac, mink gray, beige, taupe, stone, dark purple, sky blue, earth, Caribbean blue, mandarine, dusky pink, it's a color story steeped in subtlety. As beautiful on the inside as on the outside. Lest it wasn't clear, this is more than just a handbag. It's a companion for your everyday.
It is not listed on the official website and I haven't seen it at my local Dior store yet. 
