Symfony 2.0.5 has just been released.
If you are starting a new project, you can get the Symfony Standard Edition distribution on the download page.
Then, run the vendors script:
$ ./bin/vendors install
And don't forget to clear your cache:
$ php ./app/console cache:clear
Remember that the Symfony2 Components are also available as standalone
libraries. You can get them via their dedicated read-only repositories on
https://github.com/symfony/Finder for instance), install them via
pear install symfony2/Finder), or even
install them via Composer.