So I've decided to buy an x61 tablet.  I've used it for a little over a month now and here is what I think about it so far...

Pros:
- the tablet is easy to write on with the included WACOM pen.
- it's fast! it is as fast as most new desktops today - although you won't be able to play 3D graphic intensive games on it.
- it's very light.

Cons:
- the screen may take a little time to get used to.  If you get the 1400 resolution version, the resolution may be too small for your eyes - and it may take some time before you can get used to seeing small fonts.
- IBM takes way too long to ship the laptop - it took about 1 month for me to receive it from the time I ordered it.
- screen easily get's smudges on it.

Overall, this laptop is worth it.  If you're thinking about shelling out about 2k for one of these, then go ahead, you won't be disappointed.