Jay Freeman (saurik) has released some updated versions of Cydia Substrate in Cydia with some improvements and bug fixes. Three new versions were released within in the last 12 hours – version 0.9.5010, 0.9.5011, and 0.9.5012.
Starting with version 0.9.5010, Freeman added a new entry-level feature for developers called MSHookInterface
, which is presented at his training at Black Hat. Freeman has more information about it here