Until the OAuth version of Twitter4R is committed to GitHub (it's in a
half finished state locally and the work got very busy again:() and
released we are using the old fashioned way of "sourcing" Twitter
applciations which requires that you already have a Twitter source id
(they no longer give those out any more because they want everyone to
move to OAuth instead.
If you do already have a Twitter application "source" id, then you
will need to using the following inside your configure block:
conf.source = "your-source-id-that-twitter-recognizes"
Please scroll to the bottom of this page for some comments about it: