I've been plowing through the chapters at railstutorial.org and been using Rails 3.1.3 because I'm crazy and/or wanted a challenge. I managed to figure out most version problems easily but this one stumped me for a while.
In 10.4.2, Michael Hartl uses the following code to delete users:
<%= link_to "delete", user, :method => :delete, :confirm => "You sure?",
:title => "Delete #{user.name}" %>
It doesn't work properly if you test it in the browser (chrome) and instead sends you to that user page.
It is supposed to work if you include this:
<%= javascript_include_tag :defaults %>
but it fails with Rails 3.1 (it should work for Rails 3.0 though, or so I hear).