Recently the developers have been discussing the possibility of adding some additional optimizations to our i686 port to improve multimedia support. This would involve reducing the compatibility with older systems. As some of you may have heard (, Google translation ), this discussion has resulted in the decision to focus exclusively on the x86_64 port. The overall opinion of the developers is that the x86_64 port is now complete enough to justify this decision and that this is in keeping with Arch's philosophy of supporting current generation hardware. The x86_64 architecture has been available since 2002 (compared to i686 which is from 1995), and we believe most of our i686 users have x86_64 compatible hardware.
An official time-line for the deprecation of the i686 port has not been established, but an official announcement needs to be made, as the decision has already been leaked to the ArchLinux-BR community. However, it is likely that major updates (GNOME, KDE, Xorg, etc) will not be built for i686 in the immediate future. Users will still be able to build packages for i686 packages using ABS. As most of the architecture specific patches are for x86_64, this should be relatively pain free.