people and companies trademark shapes all the time. E.g. Apple trademarked the three-dimensional shape of the iPod. Toblerone, a company which manufactures chocolate bars with a distinctive triangular shape was able to trademark their shape.

Traditional trademarks have generally been granted for two-dimensional designs (logos, etc. - called "conventional trademark" so actually trademarking the shape of the iPod is new and called "non-conventional". One key advantage of the trademark over patents is that while the latter expire after a period of time, a trademark can be continually renewed.