Drupal using Symfony2 HttpFoundation is huge
Drupal is big, no question. Over the last years Drupal has become one of, if not THE leading CMS. Now imho one of the reasons for its success is that it's a huge enabler for non programmers to get setup with a gigantic set of features. But here at Liip our bread and butter is highly customized applications or in other words if you can get your project done by installing a bunch of Drupal modules, then we are not the right shop to go to. We do however use Drupal when it's the best starting point for development like we did with Migipedia. However we have in many situations found that we could more efficiently implement custom logic outside of Drupal and then integrate it. Now since we have chosen Symfony2 for all future custom development, the fact that Drupal8 will use Symfony'2 HttpFoundation component is huge, because it will make integration a breeze.
Basically Symfony2 converts a Request instance to a Response. So if both Symfony2 and Drupal8 use the same Request and Response classes it means that creating a sub-request and handing the response from Drupal8 into Symfony2 (or vice versa) will require no conversion at all. Now since Drupal8 will also use the Symfony2 ClassLoader component it should also be fairly easy to make the necessary instances to call into the other framework. Now if Drupal8 also adopts the HttpKernel component it will become even more natural.
Anyway check out the patch by Larry. Good times ahead.