The advanced bash scripting guide is currently 4.0, however the newest version in portage is 3.7, so it could use a bump :) Thanks
For the record: I copied the 3.7 ebuild into my overlay and renamed it to 4.0. It emerged fine.
*abs-guide-4.0 (01 Jul 2006) 01 Jul 2006; Aaron Walker <ka0ttic@gentoo.org> -abs-guide-3.6.ebuild, +abs-guide-4.0.ebuild: Version bump; tidy old ebuild. Closing that bug.