The JS in truffle_eth_class2/s08/l06-listen-to-events/index.html uses
web3.eth.compile.solidity(contract_code);
which fires a JS error and is not available any more, according to https://github.com/ethereum/go-ethereum/issues/3793 . It seems like compilation via the RPC is gone altogether. The JS already contains the commented bytecode, so it's easy to get that working again.
More precisely, running a instance=Geth/v1.7.3-stable-4bb3c89d/linux-amd64/go1.9.2 I get Error: The method eth_compileSolidity does not exist/is not available when clicking on Deploy new contract.
The JS in
truffle_eth_class2/s08/l06-listen-to-events/index.html
useswhich fires a JS error and is not available any more, according to https://github.com/ethereum/go-ethereum/issues/3793 . It seems like compilation via the RPC is gone altogether. The JS already contains the commented bytecode, so it's easy to get that working again.