I have the same error, running on Ubuntu.
I took the example config file, put in the appropriate keys and CERT directory, placed it in my home dir in ~/s3conf/s3config.yml, and ran this as a test (let's back up the s3sync dir):
I got the following:
/usr/lib/ruby/1.8/yaml.rb:133:in `load': syntax error on line 3, col -1: `' (ArgumentError)
from /usr/lib/ruby/1.8/yaml.rb:133:in `load'
from /usr/lib/ruby/1.8/yaml.rb:144:in `load_file'
from /usr/lib/ruby/1.8/yaml.rb:143:in `open'
from /usr/lib/ruby/1.8/yaml.rb:143:in `load_file'
from /home/blueplate/s3sync/s3config.rb:17:in `each'
from ./s3sync/s3sync.rb:28:in `require'
I can't tell from the error what's going on. Is it not seeing my conf file? Is the file corrupt? Pointers appreciated.