Hi Developers,
Shopify is continuing to grow, causing our concerns for security to become increasingly important for both our merchants and our developers. With this in mind, we are asking that you update your applications to use OAuth, as our legacy authentication system is deprecated and will be unusable as of February 15, 2014. If you are already using OAuth (most of you!), you can safely disregard this. Please refer to the following documentation for instructions on Migrating from Legacy to OAuth. As well, do not hesitate to get in touch if you run into issues or problems, we'd be happy to help out.
Cheers,
Shopify Apps Team