Can Wall of Force be placed in contiguous segments but with 90 degree bends? For example, can Wall of Force be placed in a closed rectangular pattern? How about an "L" or "T" or "E" shape? Can segments be stacked to get a height greater than 10'? Or must all segments be placed in a straight line with no bends?
The caster can form the wall into a flat, vertical plane whose area is up to one 10-foot square per level.
In bed, so I can't double check the wording in the rulebook with that of the SRD but the sentence quoted would read to me that the wall must indeed be a flat and vertical plane which would mean no corners. That's my take on it, anyway.
As for stacking, I'd have no issue with there being multiple walls stacked atop on another, although depending on your level I think it'd have pretty minimal use.