still looking for a Newton successor...

form factor should be comparable to a Paperback book, roughly 16*10*1,2 cm. Screen should be 1280*768 with 217 dpi. Bluetooth, IEEE802.11g and IRda built in. MacOSX would be fine, but only with Hypercard and LISP. Update n 1/2012: Samsung Galaxy Note seems to be pretty close. No IR, just Android, but VNC to a Mac should give access to MacOSX and via virtual machines (Parallels, VMware, VirualBox) you can use Solaris, Linux and Windows, too.