A typical release tarball (or zipball) currently contains the following:
bitcoin-0.12.1/
bitcoin-0.12.1/bin/
bitcoin-0.12.1/bin/bitcoin-cli
bitcoin-0.12.1/bin/bitcoind
bitcoin-0.12.1/bin/bitcoin-qt
bitcoin-0.12.1/bin/bitcoin-tx
bitcoin-0.12.1/bin/test_bitcoin
bitcoin-0.12.1/include/
bitcoin-0.12.1/include/bitcoinconsensus.h
bitcoin-0.12.1/lib/
bitcoin-0.12.1/lib/libbitcoinconsensus.so
bitcoin-0.12.1/lib/libbitcoinconsensus.so.0
bitcoin-0.12.1/lib/libbitcoinconsensus.so.0.0.0
I think we should add a README.md with the release that describes how to get started, and what every file is for.
For windows we have doc/README_windows.txt which gets packaged as part of the installer. It is not packaged as part of the windows zips though.