What is changing?Silver and Gold users: no change, all of your API calls are handled by api.thumablizr.com.
Unregistered and free users: There will be no major change. The API stays the same. Screenshots should be faster and more reliable after the migration.
Just after the migration, some of the screenshots requested recently might not be available, a new screenshot request will be done on the new platform.
Let us know if you find any difference in behavior after the upgrade on 03/27/2014 at 9:00pm PST.