[blocks B     ] <sys-fs/udev-115-r1 (is blocking sys-fs/device-mapper-1.02.22-r5)
[blocks B     ] <net-print/hplip-1.7.4a-r1 (is blocking net-print/cups-1.3.5)
[blocks B     ] >=x11-base/xorg-server-1.4 (is blocking x11-base/xgl-0.0.1_pre20070105)
[blocks B     ] x11-misc/xkbdata (is blocking x11-misc/xkeyboard-config-1.1)
[blocks B     ] >=sys-apps/util-linux-2.13_pre (is blocking sys-process/schedutils-1.5.0)
[blocks B     ] <sys-fs/device-mapper-1.02.19-r1 (is blocking sys-fs/udev-118)
[blocks B     ] sys-apps/mktemp (is blocking sys-apps/coreutils-6.10-r1)
[blocks B     ] x11-misc/xkeyboard-config (is blocking x11-misc/xkbdata-1.0.1)
[blocks B     ] <sys-apps/baselayout-2.0.0_rc (is blocking sys-apps/makedev-3.23.1)
[blocks B     ] sys-process/schedutils (is blocking sys-apps/util-linux-2.13.1)
[blocks B     ] >=sys-apps/coreutils-6.10 (is blocking sys-apps/mktemp-1.5)

 * Error: The above package list contains packages which cannot be
 * installed at the same time on the same system.

For more information about Blocked Packages, please refer to the following
section of the Gentoo Linux x86 Handbook (architecture is irrelevant):

http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?full=1#blocked