Mac – Where does macports install programs

This problem sounds like you did not set up dbus yet. Read the output of the command port notes dbus and follow the instructions.

$ port notes dbus
dbus has the following notes:
  ############################################################################
  # Startup items have been generated that will aid in
  # starting dbus with launchd. They are disabled
  # by default. Execute the following command to start them,
  # and to cause them to launch at startup:
  #
  # sudo launchctl load -w /Library/LaunchDaemons/org.freedesktop.dbus-system.plist
  # launchctl load -w /Library/LaunchAgents/org.freedesktop.dbus-session.plist
  ############################################################################

The issue is that you are trying to compile for the ppc architecture thus the error in cross-compiling.

Did you upgrade to Snow Leopard leaving macports on - the only way to upgrade macports across operating systems is to reinstall.

Otherwise did you choose the correct dmg to install from - it is OS dependant.

Otherwise you need to look at /opt/local/etc/macports/macports.conf and see what build_arch is set to. The default (or not set) on a new Snow Leopard macports install is 32 or 64 bit Intel code depending on the CPU you have.