Yes...what Aethien said. In the context of games in particular it is characterized by video games that are largely identical to one another but use different skins or motifs. For instance, while Street Fighter II (and it's more famous follower Mortal Kombat) started it's own particular type of arcade fighting game several other like games rose that were largely the same fare but with different graphics and/or settings.
In WoW this seems more or less to pertain to the types of Talents one chooses to better fill their character's abilities. Most Hunters seem to follow the same basic recipe for maximization of a certain set of atributes that help them to fill a better role in a group or raid.
In layman's terms, it means the average Hunter you run across is probably going to have the same basic talent build as the next Hunter, for the most part. Thus it makes the whole group rather homogenous...hence the descriptive phrase, "cookie cutter", which Aethien was able to describe in only a fraction of the sentences that I myself used. :)