We've generated a new set of profiles for Gentoo installation. These are now called 13.0 instead of 10.0, e.g., "default/linux/amd64/10.0/desktop" becomes "default/linux/amd64/13.0/desktop".
Everyone should upgrade as soon as possible. This brings (nearly) no user-visible changes. Some new files have been added to the profile directories that make it possible for the developers to do more fine-grained use flag masking (see PMS-5 for the details), and this formally requires a new profile tree with EAPI=5 (and a recent portage version, but anything since sys-apps/portage-188.8.131.52 should work and anything since sys-apps/portage-184.108.40.206 should be perfect).
Since the 10.0 profiles will be deprecated immediately and removed in a year, emerge will suggest a replacement on every run. I strongly suggest you just follow that recommendation.
One additional change has been added to the package: the "server" profiles will be removed; they do not exist in the 13.0 tree anymore. If you have used a server profile so far, you should migrate to its parent, i.e. from "default/linux/amd64/10.0/server" to "default/linux/amd64/13.0". This may change the default value of some use-flags (the setting in "server" was USE="-perl -python snmp truetype xml"), so you may want to check the setting of these flags after switching profile, but otherwise nothing happens.