Releasing this version primarily to address #1881154: Data source selection lost on "Edit Subpage", and to add the first attempt at Features support. This is incomplete and poorly documented, but I haven't had any time to make more progress on it in two months, so I'm putting this out there in hopes that some people will give it a try.
Updated to use CTools plugins to provide content and configuration for subpages. This version includes the same functionality as 1.x, but the underlying code was largely re-written.
If upgrading from 1.x: Make sure that CTools is enabled, and run the update process. Any existing subpage configuration will be converted to the new format in the database, and continue working as it did before.
This is being marked as beta because I have only tested it myself. I would love to get some feedback from anyone else who tries it out.
Initial release of 7.x port. This is marked as an alpha since this was all done today and has only been tested in my local dev environment. I hope that some of the people who requested a 7.x version can give it a spin and help tease out any bugs that may remain, so that I can do a full release.
This module is in use on the Drug Policy Alliance website and has been rigourously tested. However, that version of the module had the subpage configuration coded in; before releasing it here on d.o, I built an admin interface to manage the subpages for each content type.