Please stabilize sys-apps/portage-2.1.11.55. The most important fixes in this release are for bug 459832 (autounmask and world file interfere with slot-operator rebuilds) and bug 460304 (endless networkmanager rebuilds triggered by slot-operator deps conditional on USE=wimax). Bug 459934 tracks all bugs fixed since 2.1.11.52.
amd64 stable
x86 stable
Stable for HPPA.
arm stable
Marked ppc/ppc64 stable.
See bug 467144 for next stable request.