Cubicles (and other temporary walls) are deductible while they are being used.  Walls, doors and other permanent improvements are only tax deductible when the company sells it's facilties or moves out when the lease is up.

It's just not worth the money to have real walls for most people.

Anything else that is said about one study or another is just BS to hide the fact that it's all about money.

Here's a link to someone who can say it better than I JOS