What is Lacewing?
liblacewing is a cross-platform, high-level networking library for C and C++.
It aims to provide a set of straightforward classes for network communication, with a focus on scalability and platform specific optimisations (such as support for IOCP, epoll and kqueue).
Lacewing is open source under a BSD-style license.
Where can I get it?
The current version is 0.5.1 (release notes - zip - tarball).
Other versions are available over at GitHub. The latest commit for each released version is labeled with a tag, or you can just take the HEAD (which should always at least compile, but may not match the documentation).
Is there any documentation?
Yep, right here.
You might also want to read the FAQ.