I'm all for new features, but the backwards breaking change in Rack::Static goes beyond me.

use Rack::Static, :urls => ['/css/', '/graphics/', '/js/'], :root => "public"
That line has been sitting in my dev environment for the last year, working like a charm, upgraded Rack and bam, now all requests are looking for index.html.

To me it makes absolutely no sense that '/' is mapped to index.html by default, it should only be relevant if you've specified :index.
Why is index.html the default setting?