eix dev-lang/perl
[I] dev-lang/perl
     Available versions:  [M]5.8.8-r8 [M]~5.10.1 [M]5.12.2-r6 [M]~5.12.3 5.12.3-r1{tbz2} {berkdb build debug doc elibc_FreeBSD gdbm ithreads perlsuid}
     Installed versions:  5.12.3-r1{tbz2}(12:07:05 19.05.2011)(berkdb gdbm -build -debug -doc -ithreads)
     Homepage:            http://www.perl.org/
     Description:         Larry Wall's Practical Extraction and Report Language

emerge -uavDN @world

These are the packages that would be merged, in order:

Calculating dependencies... done!

!!! All ebuilds that could satisfy "~dev-lang/perl-5.12.2" have been masked.
!!! One of the following masked packages is required to complete your request:
- dev-lang/perl-5.12.2-r6::gentoo (masked by: package.mask)

(dependency required by "virtual/perl-Sys-Syslog-0.27" [installed])
(dependency required by "dev-perl/DBI-1.615" [installed])
(dependency required by "dev-perl/DBD-mysql-4.01.7" [installed])
(dependency required by "dev-db/mysql-5.1.56" [binary])
(dependency required by "virtual/mysql-5.1" [installed])
(dependency required by "media-sound/amarok-2.4.1" [ebuild])
(dependency required by "app-misc/cl-multimedia-meta-11.6" [binary])
(dependency required by "app-misc/cld-meta-11.6" [binary])
(dependency required by "app-misc/calculate-meta-11.6" [binary])
(dependency required by "@selected" [set])
(dependency required by "@world" [argument])
For more information, see the MASKED PACKAGES section in the emerge
man page or refer to the Gentoo Handbook.