Symfony 1.1 new features:

Command Line Utility rewritten from scratch. Now it’s based on a new, totally extensible, Object-Oriented subframework.

As many of you know, the most important enhancement in this new release is the new Form sub system.
From now, form helpers are deprecated. Form are now classes and Form Widgets offer native and easy handling of validation, filling, request binding, CSRF protection, file upload validation.

Plugin manager has been rewritten too. Now supports dependecies between differents plugins.

In symfony 1.1 propel is a plugin, bundled in the lib folder of Symfony 1.1 ( you don’t need to install it ).
Schema structure has been improved: now you can declare behaviours directly in the schema and a schema can overwrite others.

Routing has been improved with a cache layer. Finally we can change ‘/’ character in urls with any character.

Internationalization now has 2 new usefull tasks: i18n:find ( find all strings without __() ) and i18n:extract that find untranslated texts.
I18n now uses the same view caching system and I18n class is not a singleton.

Caching has been impoved too. Now view cache manager accepts wildcards in remove() calls and you can remove the cache from other applications.
Caching factories allow you to use differents caching storage and function cache can now use any caching factory.

YAML parser is now more robust and errors in YAML now throw helpful error messages.
All config.php disappeared: project and application configurations are now classes and other applications can access to them.

Has been written a performance tool and a lot of unit tests ( more of 8000 ).

Another very important point in symfony 1.1 new features is the new event manager inspired by Cocoa.

These are the principal new features of Symfony 1.1 but as Fabien say: the beauty is inside.