Как я понял, недавно в gentoo убрали kde-4.4, остался только слот 4.6, который переименовали в 4. Всё это у меня произошло при очередном emerge --sync. А эта запись это и показывает.
Смотри как изменилась версия пакета: 4.6.3(4.6) -> 4.6.3(4).
Была версия 4.6.3 в слоте «4.6», а стала версия 4.6.3 в слоте «4».
[><] == foo/bar (1.1(1) 2.0(2) -> 1.0(1) 2.1(2)): description
The status of package foo/bar has changed in the tree (for your settings): The symbols on the left mean that one slot has gained a higher
version which could be installed without modifying masks/keywords, another slot had such a highest version removed. If you consider the
version strings, it becomes clear that slot 2 has obtained a new version (the previous stable in this slot was 2.0, the new one is 2.1),
and that the previously highest stable version 1.1 of slot 1 was removed or masked (the current stable version in this slot is now 1.0).