Most probably the superkaramba package is depending on newer kde-libs and wants to pull it in,
and the kde-libs 3.5.5 are in conflict with kde-env package, that problem is discussed here intensively, search and you will find
the quick resolution for you is either:
1. unmerge kde-env and then update all you kde packages (you can use kde-meta package which will pull everything), but don't restart your X or you will lose settings like icons and fonts, before you complete the upgrade (they will be restored however once you finished upgrading), or
2. if you are happy with your current kde version you can tell emerge to install older version of superkaramba, something like
# emerge -a =kde-base/superkaramba-3.5.2
this is the previous version.
Or you can just wait for sabayon 3.2 mini, or download sabayon 3.2 dvd with bittorrent.