libuv is part of the Node project: http://nodejs.org/
libuv may be distributed alone under Node's license:

====

Copyright Joyent, Inc. and other Node contributors. All rights reserved.
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to
deal in the Software without restriction, including without limitation the
rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
IN THE SOFTWARE.

====

This license applies to all parts of libuv that are not externally
maintained libraries.

The externally maintained libraries used by libuv are:

  - tree.h (from FreeBSD), copyright Niels Provos. Two clause BSD license.

  - ngx_queue.h (from Nginx), copyright Igor Sysoev. Two clause BSD license.

  - c-ares, copyright Daniel Stenberg and others. MIT licensed.

  - libev, located at ev/ is copyright Marc Alexander Lehmann, and
    dual-licensed under the MIT license and GPL2.

  - libeio, located at eio/ is copyright Marc Alexander Lehmann, and
    dual-licensed under the MIT license and GPL2.