Reinstalling the packages that were reported by debsums to be corrupted fixed the situation so, that debsums doesn't find any corruption anymore. However, after a *clean* reboot to gentoo install cd, and running xfs_check from there for the root filesystem, yet again shows corruption similar to what Richard Ayotte reports above. Before updating anything, the filesystem was xfs_repair'ed and xfs_checked before boot into ubuntu, so, it definitely was ok.
Reinstalling the packages that were reported by debsums to be corrupted fixed the situation so, that debsums doesn't find any corruption anymore. However, after a *clean* reboot to gentoo install cd, and running xfs_check from there for the root filesystem, yet again shows corruption similar to what Richard Ayotte reports above. Before updating anything, the filesystem was xfs_repair'ed and xfs_checked before boot into ubuntu, so, it definitely was ok.