UPDATE – The 10.9 Mavericks binary is now available here.
If you try installing or updating MacPorts ports after upgrading OS X to 10.9, you’ll hit an error with gnutar:
The recommended fix from MacPorts is to reinstall MacPorts and all ports after a major OS upgrade. Unfortunately there is no binary for Mavericks yet and quite a few ports are failing to build right now including MySQL 5.6 and Python 2.7.
The  workaround is to keep your current MacPorts installation and install gnutar from source:
This is definitely not a long term solution and should really just be used for new ports that are must haves. I wouldn’t run port upgrade outdated or try to upgrade any specific ports as you will find that not all ports will build.
Once a Maverick’s binary is out, be sure to remove this gnutar before doing the migration.
Read more discussion of MacPorts on Mavericks.
Note: Be sure to build and install gnutar from source and not just symlink…
thanks for this note, clears up a couple of days of struggle