Provide a migration path for users from Subscription module

There is the http://drupal.org/project/subscription module which I use on a site or two (or three). I'm starting to upgrade these sites and am planning to move them to Subscriptions module. This is a placeholder to perhaps get some help from other people and also put the results of my efforts to create a migration tool from Subscription to Subscriptions.

If there's been work in this area already - please let me know.