In case you haven't already noticed, Blender 2.73 was released a few days ago with the Stage I improvements for Grease Pencil.
Grab a build from Blender.org, or check out the release notes for an overview of what's been added so far.
In other news, work on Stage II is in progress now. Most notably, there is now a copy and paste buffer in place, and color swatches are now displayed for both strokes and fills. More work is taking place when and where possible (in between trying to wrap up the core of the depsgraph, and soon resuming my uni research commitments). If you've got any feedback, suggestions, or would like to discuss ways we could develop these tools, feel free to send an email to the bf-animsys mailing list.