I have a brand new Lenovo ThinkPad T530 and it's running Fedora 18 flawlessly. Wi-Fi, headphone plugged-in sensor, OSD, media keys, dual-monitor support, webcam, 3D acceleration, sleep/wakeup, all working since day 1 out of box.
I think the more business oriented laptops are safe to run Linux and the new XPS 13 doesn't look bad at all except for the pricing.
EDIT: My biggest issue with Linux is font rendering, which, out of the box, sucks. The day I discovered http://www.infinality.net/blog/ I was the happiest man at the office.
This isn't really any different from OSX in that there is literally only one hardware platform on which that OS is supported out of the box.
Before the era of the Linux on the desktop comes, we need an actual Linux desktop. Trying to target a whole host of hardware is too hard and unnecessary anyway - just copy Apple's strategy and let's move on to problems that are actually worth solving.
My ThinkPad X1 Carbon worked perfectly out of the box, including wifi, bluetooth, sleep/wake, media keys, 3d acceleration, external displays, webcam, mic, etc. It also gained an hour over its Windows 7 battery life.
I've never had problems with sleep/wakeup (except bugs in the firmware). Battery life is equal if not better than under windows. Developers rarely need 3D acceleration, and for most webgl demos and games the intel open source driver does just fine.
http://randomtristan.blogspot.com/2013/01/my-review-of-dell-... (reports around 3 hours)
http://www.pcmag.com/article2/0,2817,2400986,00.asp (tested at 6 hours).
Acer Timeline 1810TZ, Acer Timeline 3810TZ, Sony Vaio VPC-J1, Lenovo ThinkPad T61, Dell Precision 390, Dell Precision T3500.
All have irritating bugs, hibernation and sleep problems, random crashes despite being absolutely bog standard Intel hardware across the board supposedly fully supported by Linux. The same kit doesn't exhibit any problems under Windows.
The Timeline series machines under Windows 7 got a whopping 8-10 hours battery life of average load OUT OF THE BOX. Under Ubuntu, even with all the powertop tweaks etc, 3 hours was pushing it.
Current Ubuntu, CentOS and Debian were tried on each machine at the time.
Just can't be bothered any more. Linux (Debian) sits inside a VirtualBox VM on Windows on my T61 where ironically the battery lasts longer when it's in a VM than on bare metal...