I have followed the tutorial exactly like they showed in their page:
http://truffleframework.com/tutorials/pet-shop
except the following changes because they use "ganache" (currently bugged and unavailable) and I chose "test-rpc":
In "truffle.js" port: 8545
In "src/app.js" App.web3Provider = new Web3.providers.HttpProvider('http://localhost:8545');
The "adopt" button in the front-end UI doesn't prompt the transaction with metamask.
This was an issue because of a misplaced "view" classification. Please see https://github.com/trufflesuite/trufflesuite.com/pull/52 and it should work. "Removed the "view" word from line 130. With the word view in there, you can never click the adopt button and MetaMask will never pop up."