I am a big fan of Celery for executing scheduled tasks in Django. I am now using Symfony 2 and see that it is almost similar to Django framework.
I wonder if there is something similar to Celery in Symfony for scheduling task queues.
Celery is providing a simple layer to use messaging. It makes the task of building async services easy. Interestingly the concept is not new. It is already available in form of standard protocol like AMQP. Documentation available at
http://php.net/manual/en/book.amqp.php
Although I can't vouch for it but potentially you could hookup PHP and Python code as publisher and subscriber, thus using Celery for doing the task while PHP code could issue it.
You can use a simple implementation of Queues, based in Redis.
I recommend you use Beanstalkd.
You can use LeezyPheanstalkBundle or PheanstalkBundle.
or you can check other clients: