Been using MacPorts for installing my *nix software on OS X happily for a few months, made the jump to Mavericks last weekend and realized that it broke my macports. So it looks like you need to update to a new version of macports via the download and install on top of it as the port selfupdate command will not work for a 10.x version bump.

sgwilbur@gura:~$ sudo port version 
Version: 2.2.0
Follow on error, now after updating to 2.2.1 I still get errors attempting to run:
sgwilbur@gura:~$ sudo port upgrade outdated
Password:
--->  Building ncurses
Error: org.macports.build for port ncurses returned: command execution failed
Please see the log file for port ncurses for details:
    /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_devel_ncurses/ncurses/main.log
Error: Unable to upgrade port: 1
To report a bug, follow the instructions in the guide:
    http://guide.macports.org/#project.tickets

Turns out this requires and update to the xcode cli tools that was not updated automatically, check out this macports ticket #40843

sgwilbur@gura:/opt/local$ xcrun --show-sdk-version
10.8
sgwilbur@gura:/opt/local$ xcode-select --install
xcode-select: note: install requested for command line developer tools

At this point you are prompted with a dialog to either try and update or view the updates in the app store, I tried to get the update once or twice whilst I was moving around and potentially dropped the connections, once I got settled I just went to the app store and updated XCode and not suprisingly..

sgwilbur@gura:~$ sudo port version 
Version: 2.2.1
sgwilbur@gura:/opt/local$ xcrun --show-sdk-version
10.9

Now it works when you try and upgrade outdated

sgwilbur@gura:/opt/local$ sudo port upgrade outdated
Password:
...

Back to happy state!