Released versions of NetworkExpect (in source code form) can be downloaded from http://www.netexpect.org/downloads/. See the PortabilityPage for information and tips on how to build NetworkExpect.
The NetworkExpect source code is maintained in a Subversion repository. This repository is currently not available to the community, but this may change depending on the interest from the community.
Binaries for some operating systems will be provided at some point. Contributors are welcome.