I don't think that my bike is among the lightest ones. However it is a disc brake bike so I feel that it would be good contribution to this thread as there aren't so many disc brake bikes yet. And they say disc braking is the future so here it goes. Pacman and Pinky likes the bike too.
Also you should note that my focus has been on practicality and durability rather than on weight. Also things like power meter bring in more weight. The ST-R785 / BR-R785 combo is also very heavy when compared to cantilever setup. Also the cockpit is aluminium because it is cheaper to crash
My bottom line is: disc brake CX bikes can be lighish too. Maybe not near the lighter end of 7 kg but almost.
My bike weighs 8.2 kg in total. Sorry for not weighing all the parts separately. EDIT 2014-10-17: updated pictures.
* Frameset: Ridley X-Fire (50), 1260g (with bottle cage bolts and seatpost collar)
* Fork: Ridley X-Fire/4ZR, 560g uncut
* Brake / shifter levers: Shimano ST-R785
* Crankset: Power2Max Type S Rotor 3D+, 110 BCD 172.5 mm, 610g (crankset + spacers + bolts + Power2Max spider)
* Chainrings: Rotor Q-Rings, 34/46 (will change to Q-Rings 36/46 as the 34 is too small)
* Front derailleur: Shimano Dura-Ace Di2, FD-9070
* Rear derailleur: Shimano Dura-Ace Di2, RD-9070
* Chain: Shimano Dura-Ace, CN-9000
* Brakes: Shimano BR-R785
* Brake rotors: Avid HS1, 160 mm
* Handlebar: Zipp Service Course SL-70 Ergo, 40 cm
* Stem: Zipp Service Course SL stem, 90 mm
* Seat post: Zipp SLSPEED, 20 mm setback
* Saddle: old Selle Italia SLR Kit Carbonio Flow
* Pedals: Crank Brothers Eggbeater 3
* Wheels: Stan's NoTubes Iron Cross Comp
* Tires: Schwalbe Rocket Ron (rear), Schwalbe Racing Ralph (front), both tubeless
* Tape: Zipp CX
* Bottle Cage: some cheap plastic Elite