In all the handbook you use this command: tar xvjpf [file].tbz2 You can remove the format options and it works as well: tar xvpf [file].tbz2 It could make easier the reading of the handbook and be sure to take important options ("p").
Not sure all versions of tar are smart enough to detect gzip'ed or bzip'ed tars. Anyway, there's nothing wrong with the current tar command.
the autoguess feature is part of all stable tar packages, but that wont help people who are using another method (non-Gentoo like knoppix or something) who has a tar that is outdated personally i love not having to type j or z or whatever, but having it in the handbook is a safe move
