Gentoo ~ # emerge --ask xorg-x11

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

Calculating dependencies /
!!! All ebuilds that could satisfy "x11-drivers/xf86-video-intel" have been masked.
!!! One of the following masked packages is required to complete your request:
- x11-drivers/xf86-video-intel-1.6.0_alpha20060614 (masked by: missing keyword)
- x11-drivers/xf86-video-intel-1.6.0_alpha20060413 (masked by: missing keyword)

For more information, see MASKED PACKAGES section in the emerge man page or
refer to the Gentoo Handbook.
(dependency required by "x11-base/xorg-x11-7.0-r1" [ebuild])


Here's my package.keywords (I just paste the lines about this package ):
 =x11-drivers/xf86-video-intel-1.6.0_alpha20060614 ~x86
 =x11-drivers/xf86-video-intel-1.6.0_alpha20060613 ~x86

and the same configuration lines from the package.unmask :
=x11-drivers/xf86-video-intel-1.6.0_alpha20060614
=x11-drivers/xf86-video-intel-1.6.0_alpha20060613 

Portage seems to don't mind the ~x86 keyword, wherever I write it, in unmask or either keyword or both.