It's been used successfully in the past, but this has more to do with the amount of effort/money expended by the owners to grow the brand than any intrinsic value of the domain. I'm thinking most of the successful examples were hand regs or acquired very cheaply, so the companies could focus their limited funds on advertising/branding rather than blowing a huge chunk on a domain name. A brandable domain like that really comes with no inherent benefits by itself. It probably won't have any traffic, etc, so it's a liability from the start, not an asset.
Since there have been successful examples in the past, this may add some value to short domains of this type that make sense, but overall, like alien51 said, I think it's highly speculative.