On September 19, 2017, Dr. Christian Reitwiessner announced via reddit that Ethereum's Ropsten testnet has verified "the zkSNARK part" of a Zcash transaction. Co-creator of the programming language Solidity, Reitwiessner posted a link to the relevant code on GitHub and the relevant transaction available via Etherscan.
Reitwiessner explained, "What is verified here is the zkSNARK part of some real transaction on the real Zcash network. I pulled the data out of the chain sometime around January, I think." Reitwiessner said he has "no idea" of the transaction's participants or value, but the Ethereum network has confirmed the transaction.
When one redditor expressed concern about the high gas price, Reitwiessner explained, "The verification cost of a zkSNARKs is largely independent of the amount of computation done in a zkSNARK. This means you could bundle 10000 zk transactions and verify them in a single Ethereum transaction."