Michael Gartenberg has convinced me to put the new X41 ThinkPad Tablet PC on my short list:
This device is a no compromise system that’s perfect for business use. The Tablet functionality simply adds a hugely powerful mobile feature to what is already a killer device. Want pen based functions. You got it. Want to go ahead and type a long email with a full size ThinkPad keyboard. Done. Want to work for more than six hours on a single battery charge. It’s in there. The wonder of this machine is that it’s not revolutionary. It’s not the thinnest, lightest, cheapest or most expensive. It is the best of the breed. This is a device that will clearly be the Tablet of choice for the verticals that need the functionality immediately and I suspect this machine is the first Tablet that can be good enough over time to make inroads with horizontal mainstream users as well. The Tablet PC edition of Windows isn’t dead, it’s just been hibernating waiting for the release of this machine.
Still nothing on the Lenovo site with product details – only this Webcast.
Update: Details on the X41 Tablet (including a 3D tour) are here and full specs are here. (Thanks to jkOnTheRun for the pointer.) Up to 8.5 hours battery life? Under 4 pounds? Yes!
I am, however, steeling myself for the price tag, which I assume will be formidable.
Ed Bott 
Regarding price…FWIW, Paul Thurrott sez:
“Most interesting, the X41T will cost just $100 more than a comparably equipped X41 laptop computer. However, ThinkPads tend to be pretty expensive: The X41T will start at $1800.”
Btw, one of the best X41T features I see (besides the 6-8 hour battery life) is the integrated fingerprint reader. Logging on to my Tablet PC, which I have configured to require a complex password at startup and whenever resuming from hibernation/standby/screen saver, is frustrating because I have to flip the screen over to get to the keyboard and then type–negating the pen capability. (At the logon screen, the input panel is unavailable; the only alternative is to hunt and peck using the on-screen keyboard.) I use fingerprint readers on my desktop PCs, where they’re a great convenience. After using a Tablet PC for a few months, I’d consider a fingerprint reader to be a necessity on my next one.