Last night on #Postchat the amazing @AdobeAE answered a plethora of questions about the newest release of After Effects CS6.
One question that came up was if you can bend a 3d extruded layer. The answer is No.
You can now bend a 2d layer till it becomes a half cylinder, but the 3D extrusions do not have that option.
Depending how far you need to go there are some workarounds
This was a quick test of an element for the course over at FXPHD.com
If you create a small span. Then a null and made it 3D. adjust the rotation and scaling of the null a bit and then parent the extrusion to the null it will inherit those transforms as a skew. Duplicate the span, offset, parent to the original. Then dupe, option parent. This will create a 3rd span with the same offset as the 2nd. Keep duplicating and parenting…
After you have enough spans (you can always add more later) play with the transforms of all the spans simultaneous to create a bend, or some other crazy shapes and animations
Here is a quick screencap showing how the slide can bend