Print vars to playbook logfile ?

Is there an easy way to print variables into the logfile output when
the playbook while running ?
That would really help upon debugging to see what is in a variable at
runtime....

Verbose logging improvements are going to be included in 0.5, though
in 0.4 you may wish to take a look at syslog on remote machines
coupled with the data in /etc/ansible/setup (or your local user setup
directory) where the metadata file is written.