Thibault Saunier reports on his blog that adding video effects is now working, the GTK user-interface for handling the effects is working and supports the configuring of effects, and effects can be enabled/disabled or removed. Still being worked on for the PiTiVi video effects support is seeking, drag 'n drop to the effects list, key-frame based effect configuration, and saving/opening projects containing effects.
Thibault is working on these Linux video editor improvements as part of Google's Summer of Code. The code isn't yet merged into the mainline PiTiVi code-base, but will be merged from his personal Git repository in the future when it's ready for release. Those wanting to try out the PiTiVi video editor with its new effects capabilities can fetch the code from his repository hosted at GitHub.