Sinatra is a DSL for quickly creating web-applications in Ruby with
minimal effort. e.g.,

    require 'rubygems'
    require 'sinatra'
    get '/' do
      'Hello world!'
    end

Run with `ruby myapp.rb' and view at http://localhost:4567/.

This is a major release with a good number of new features and bug
fixes. Please be sure to test your apps under the new version before
upgrading production environments.

   $ gem install sinatra

For more information about Sinatra see:

   http://sinatra.rubyforge.org/
   http://github.com/sinatra/sinatra/

Please report any issues to the Sinatra mailing list
<sinatrarb / googlegroups.com> or open a ticket in lighthouse:

   http://sinatra.lighthouseapp.com/

Huge thanks to everyone that helped out with this release by testing,
reporting bugs, submitting patches, etc. We were able to make some large
and invasive changes to the codebase in a very short amount of time due
largely to everyone's willingness to help out.

From the CHANGES file:

 * Works with and requires Rack >= 0.9.1

 * Parameters with subscripts are now parsed into a nested/recursive
   Hash structure. e.g., "post[title]=Hello&post[body]=World" yields
   params: {'post' => {'title' => 'Hello', 'body' => 'World'}}.

 * Regular expressions may now be used in route pattens; captures are
   available at "params[:captures]".

 * New ":provides" route condition takes an array of mime types and
   matches only when an Accept request header is present with a
   corresponding type. [cypher]

 * New request-level "pass" method; immediately exits the current block
   and passes control to the next matching route.

 * The request-level "body" method now takes a block; evaluation is
   deferred until an attempt is made to read the body. The block must
   return a String or Array.

 * New "route conditions" system for attaching rules for when a route
   matches. The :agent and :host route options now use this system.

 * New "dump_errors" option controls whether the backtrace is dumped to
   rack.errors when an exception is raised from a route. The option is
   enabled by default for top-level apps.

 * Better default "app_file", "root", "public", and "views" location
   detection; changes to "root" and "app_file" automatically cascade to
   other options that depend on them.

 * Multiple Sinatra applications can now co-exist peacefully within a
   single process. The new "Sinatra::Base" class can be subclassed to
   establish a blank-slate Rack application or middleware component.
   Documentation on using these features is forth-coming; the following
   provides the basic gist: http://gist.github.com/38605

 * Error mappings are now split into two distinct layers: exception
   mappings and custom error pages. Exception mappings are registered
   with "error(Exception)" and are run only when the app raises an
   exception. Register custom error pages with "error(status_code)",
   where "status_code" is an integer; custom error pages are run any
   time the response has the status code specified. Or, register an
   error page for a range of status codes: "error(500..599)".

 * In-file templates are now automatically imported from the file that
   requires 'sinatra'. The use_in_file_templates! method is still
   available for loading templates from other files.

 * Sinatra's testing support is no longer dependent on Test::Unit.
   Requiring 'sinatra/test' adds the Sinatra::Test module and
   Sinatra::TestHarness class, which can be used with any test
   framework. The 'sinatra/test/unit', 'sinatra/test/spec',
   'sinatra/test/rspec', or 'sinatra/test/bacon' files can be required
   to setup a framework-specific testing environment. See the README
   for more information.

 * Added support for Bacon (test framework). The 'sinatra/test/bacon'
   file can be required to setup Sinatra test helpers on Bacon::Context.

 * Deprecated "set_option" and "set_options"; use "set" instead.

 * Deprecated the "env" option ("options.env"); use "environment"
   instead.

 * Deprecated the request level "stop" method; use "halt" instead.

 * Deprecated the request level "entity_tag" method; use "etag" instead.
   Both "entity_tag" and "etag" were previously supported.

 * Deprecated the request level "headers" method (HTTP response
   headers); use "response['Header-Name']" instead.

 * Deprecated "Sinatra.application"; use "Sinatra::Application" instead.

 * Deprecated setting Sinatra.application = nil to reset an application.
   This should no longer be necessary.

 * Deprecated "Sinatra.default_options"; use
   "Sinatra::Default.set(key, value)" instead.

 * Deprecated the "ServerError" exception. All Exceptions are now
   treated as internal server errors and result in a 500 response
   status.

 * Deprecated the "get_it", "post_it", "put_it", "delete_it", and
   "head_it" test helper methods. Use "get", "post", "put", "delete",
   and "head", respectively, instead.

 * Removed Event and EventContext classes. Applications are defined in a
   subclass of Sinatra::Base; each request is processed within an
   instance.

Thanks