Airport Utility 6.0 was released a few days ago.
You may want to keep both 5.6 and 6.0 versions. I used Pacifist, and manually reinstalled the 5.6 version side by side. Lots of missing features in the new utility. No way to tweak wireless options for Mode, Frequency, Multicast Rate or Transmit Power, and such a tiny window for port mapping list. An elegant interface, but at a price.
For a thorough review and pointers to stand alone updates, read here.
[crarko adds: Consider this a public service announcement. It also appears that AirPort Utility 6.0 only functions with the 802.11(n) compatible base stations, so that old AirPort Express you may have (like I do) is not supported. I've actually saved many older versions of the utility, even for the original Graphite (flying saucer) bases.]
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