There really is no "gateway software". There's just the rippled software. To my knowledge, we have not distributed the binary to anyone who has not also received the source. In any event, the only licenses the rippled software source code is subject to are:

1) The OpenCoin license.
2) The OpenSSL license.
3) The Boost license.
4) The LevelDB license.
5) The Bitcoin license.

Rippled also uses SQLite3 and json-cpp which are in the public domain. Additional licenses might apply to the JavaScript unit tests.

Update: As there seems to be some confusion, the portions of the Rippled source developed by OpenCoin are *not* available under an ISC-like license yet. The OpenCoin license on the server source is still strictly proprietary. This will change, but it has not changed yet.