It is a particularly good idea for Print media, since users will have to manually enter the domain name. In that case, shorter is obviously better.
In online media, where a user can simply click, we've found better results using the primary domain name. That being said, as long as you aren't doing 301s en masse to the point that Google will think you are exploiting/gaming the system, it is not a 'bad' practice. Keep in mind, though, that while 301s SHOULD ensure that any link juice developed for the re-directed URL is passed on to the main URL, there is always the risk of less-than-100% transfer, or no transfer whatsoever.
Make sure you consider the risk/reward ratio for this strategy. Will you generate enough additional penetration because of the use of the shorter re-directed URL to offset the risk of diluting or getting marginal results of out the links/articles/etc? If so, go for it. If not, be safe and use the primary URL. Whatever you do, remember that as Tom said above, quality is key.