Installing fresh hot Debian 7.0 on a shiny new ThinkPad X1 Carbon laptop turns out to be easy as cake. You just need to make sure to grab the wifi firmware from unstable instead of the all-in-one firmware tarballs, which contain a version that is missing a couple required files.
wget http://cdimage.debian.org/debian-cd/7.0.0/multi-arch/iso-cd/debian-7.0.0-amd64-i386-netinst.iso dd if=debian-7.0.0-amd64-i386-netinst.iso of=/dev/sdb
(Make sure /dev/sdb is really the usb stick you want to overwrite with the installer!)
And put that on a second usb stick for the installer to load the firmware off of.
As far as I can tell, everything works. (Did not mess around with the fingerprint reader, don't care.)