Lenovo's X200s, announced at the same time as the X200t Tablet PC, aims to take the ethos of the company's standard X200 ultraportable and instill some stamina into it. By switching out the standard CPU for a low-voltage processor, using an LED backlight for the display and strapping in a 9-cell battery, Lenovo claim 13.2hrs continuous runtime; Laptop Mag have have it on the bench, and under normal conditions it coasted to 10hrs 43 minutes.
I say "normal conditions", because if you're willing to put up with some Bluetooth, WiFi, mobile broadband and audio throttling, the Lenovo Battery Stretch feature will apparently drag even more time out. Of course, none of that is any use if the X200s falls flat as a PC; happily the 1.86GHz Intel Core 2 Duo L9400 processor and 2GB of RAM, while less capable than the X200, don't make a noticeable difference in performance. One particularly neat test is running a hard-drive defragment while simultaneously watching a DVD (via an external drive, as the X200s lacks built-in optical); no audio or visual skips were observed.
The drawback, then, is the price. The X200s will cost you a not-insubstantial $530 premium over the basic X200, with the model tested coming in at $2,078. You're paying, ironically, more for less - performance, at least - but niche audiences who prize runtime above all else will seemingly find plenty to like.