In gentoolkit 0.1.17-r1, the manpage for pkg has a typographical error. In the Package Selection section, there's a blurb talking about group as posted below; -g, --group Find by goup (can be combined with other searches) It appears that it shold read "Find by group" as opposed to "Find by goup".
Fixed in the CVS. Maybe was not doc-team work, but no probs ;)