they are missing from the following website http://www.ibiblio.org/pub/Linux/distributions/gentoo/distfiles/ i thought you might have taken it out, but since it's in your latest portage, it suggests it should be there.
it's not even a package as such, just three files, really ( a bash script, a c source file and a README) which are fetched from slackware (Patrick Volkerding came up with the rpm2targz stuff, I believe).
I'll take care of this as soon as drobbins has the relevant scripts in place (which AFAIK isn't completed yet) :-)
Should be all set, pushing them to ibiblio ASAP.