phoen][x pointed this one out to me on #gentoo-dev. Perl 5.6.1, during it's test phase, does a suid check on the bin dir's to see if it can tell what uid,guid,suid,etc. files are set to. On a freshly built box, this test can fail (did for phoen][x) and halt the perl install. This does not affect 5.8 - the syntax for this test is "smarter" in 5.8. Working on a patch of -r6 now.
FYI, the problem is in op/t/stat.t - have a fix, testing now
Ooooops. Yeah, so this fix has been tested and commited already. Sorry about leaving this open so long.