The alsa-plugins package is in Portage for quite a bit now and stable already on most arches, this package not only replace alsa-jack and alsa-lib's jack useflag, but also provides a plugin for PulseAudio output, a samplerate converter and an interesting AC3 encoder plugin that allows you to output 6-channels audio through digital S/PDIF connections (optical or coaxial); without that encoder, it is not possible. It would be nice to have some note about that in the guide, as it's likely to be more of interest to users than the MIDI support. Thanks.
I'll add a bit about what you're asking for, not necessarily a complete alsa-plugins howto, but at least a note on its features; aka "what it can do for you" with maybe a link to upstream documentation on it, if there is any.
Fixed in CVS, thanks for reporting.
