Not Symbian, but hopefully of interest to any ex-Psion or ex-Nokia Communicator users, it seems the general form factor has been revived, with a new startup, PsiXpda, with photo below, offering a clamshell high spec, QWERTY-driven part-PDA, part-laptop. And, impressively, far from being vapourware, it's available next week. See below for links and details.
Bare specs include an Intel Atom processor, 1GB RAM, 16GB SSD storage, 800×480 touch screen (or you can use the capacitive track-pad in the screen bezel), backlit qwerty keyboard, Bluetooth, Wi-fi b/g, integrated 3G card, user replaceable battery, full USB port. Here's the spec sheet.
See also the PsiXpda website the @psixpda Twitter account. Oh, and catch Ewan on his travels, as he has at least one of them, apparently!
PS. Disclosure: Ewan Spence, of this parish, has been substantively involved with the PsiXpda folks in various roles. But don't let that put you off...!