IBM/Lenovo's smallest, lightest is now the X60s. It is just about the same size/weight as the Dell X1 (a tiny bit heavier at 2.69lb).

The screen isn't as wide as the Dell's at 1024x768. However you do get an Intel Duo Core processor at 1.66Ghz, compared to the Dell's 1.1Ghz single core Pentium M.

It runs 3 hours on the lightest battery that they do. Add the 0.8 lb extended life battery and it will run for 11 hours !

Eryl has the X40 at work, which the X60 is replacing. I had never considered an IBM before, but after comparing the X40 with my Dell Latitude D610 I was very impressed. When my Dell expires I will probably get something like the X60s to replace it.