A new response to an old topic.https://github.com/Sailias/bitcoin_payable
A gem I've created that can be included in a rails app.
It creates payments with unique addresses from a BIP32 Deterministic seed. These payments use different currencies to get exchanges rates from currency -> BTC.
A rake task is used to update payments every 30 mins with the BTC 24 hour weighted average while another uses https://helloblock.io
to check for payments.
It is not a shopping cart solution, but a bitcoin payment generator / processor gem that doesn't require indexing the blockchain or storing private keys on your server.