I happen to be tinkering w/ airbeams w/ the intent of using cuben. I just finished a proof of concept bladder using .5mil plastic painter's drop cloth. I was able to get an air-tight seal (submerged in water, negligible pressure applied) at the ends using double sided office tape.
Next prototype will be with a polycro bladder in a tyvek pressure sleeve. This is the equivalent of a bicycle tube inside a tire. The tube is fragile and only provides a gas impermeable membrane. The tire provides all the strength, durability and shape.
I don't see any reason cuben will NOT work. As mentioned, Nemo Equipment produces a line of air beam tents. According to their engineering page, a 2" diameter beam at 8psi is stronger than a typical aluminum pole. According to that page, a desert to arctic temperature swing only produces a 2psi change in a 2" dia volume and their design burst pressure is 20psi.
So let's do a little math:
Nominal pressure: (8 lbs / in2) * (2" dia) / 2 = 8 lbs / in
Burst pressure: (20 lbs / in2) * (2'" dia) / 2 = 20 lbs / in
That's now a linear inch along the length of the tube with the force applied across the seam down the length of the beam. The lightest cuben avail. (CT0.3K.08) lists at 35 lbs/in. So there's no question the material can withstand the pressure.
1oz cuben is considered durable enough for ground cloth. A ground cloth is subject to far more abrasion and puncture risk than any part of the tent canopy, where the poles live. 1oz cuben has a tensile strength of at least 100 lbs/in, so even if your seams are only 20% material strength (!), that's still adequate. (Worth noting: polycryo is also a favorite ground cloth material due to puncture resistance.)
Preventing a puncture at the foot of the beam is as simple as using a double layer of fabric and possibly putting a small disc of plastic in the bottom. Several options come to mind to keep the ends of the pole from shifting: guy loop, velcro, suitable pocket/sleeve in the tent/fly wall, actually sew the sleeve to the tent.
Now a little more math:
1 oz / yd2 cuben = 0.00077 oz / in2
0.45 oz / yd2 polycryo = 0.00035 oz / in2 (I weighed a piece from my local hardware store but didn't verify the dimensions)
2" dia * pi + (2 x 1/4" overhang on the seam) = 6.78in
6.78in * (0.00077 + 0.00035) = 0.0076 oz / in
In comparison, Fibraplex carbon poles list at 0.011 oz / in. Obviously, this ignores the additional weight of ferrules, ends and bungie for carbon, and seams, valves, pump, and end re-enforcement for the air beam. But it does establish a ball park weight savings of ~30% over carbon at a considerable savings in cost.
And anybody that's ever relied on a bicycle knows that a flat is hardly the end of the world :)