We're migrating the code from 1.3 to 2.0. Migrating to Zephir will make the code base more maintainable and readable, allowing us to easily add more features and release more features soon and better. By introducing Zephir, we are taking the opportunity to do something unprecedented in the PHP world, a chance to do something revolutionary as Phalcon is.
We now have about a 70% of the expected functionality implemented in Zephir, (very sure it is not perfect) but this does not stop us to continue migrating the code from 1.3 to 2.0.
If you are reading this and have experience with Phalcon Internals, please help us to finish the migration and keep 1.3 and 2.0 in sync, so we could release a 2.0.0 that implement the same functionality as 1.x.
2.0.0 branch https://github.com/phalcon/cphalcon/tree/2.0.0
This directory contains a lot of examples on how to write Zephir code: https://github.com/phalcon/cphalcon/tree/2.0.0/phalcon
This page contains the 2.0.0 evolution: https://github.com/phalcon/cphalcon/wiki/Progress-2.0