Sadly just a design study and not something we'll see announced at CTIA this week, this Nokia E97 Envelop is the work of Fabien Nauroy. Comprising a QWERTY-bearing outer casing, with an integrated basic display, the Envelop's secret is a pull-out display pane.
That pane can be left protruding but still attached - for use with the keyboard - or removed completely and passed around as a photo, video or internet viewer. It would also have its own internal storage and a desktop stand, meaning it could be used as a digital photo frame.
Nauroy envisages a leather portfolio case which would have a pocket for a second screen, so the two parts are obviously intended to be sold separately. He's certainly got the Nokia design language down to a fine art; the Finns could do worse than looking to Paris for their next inspiration.