The current version of libmapper is version 0.3, and can be downloaded here. It is licensed with the LGPL v2.1 or later. The full list of files, including any previous releases, can be found at

File Description
libmapper-0.3.tar.gz Source
(Linux / Mac OSX)
libmapper-0.2-osx-universal.dmg Binaries: Examples, Framework*
(Mac OSX, x86 architectures)

*To use mapper.framework in XCode: Drag and drop into project
under Frameworks, add to a new “Copy Files” build phase, and add to
Runpath Search Paths ”@loader_path/../Frameworks” in the project's
linker properties. Binaries: DLL*
(Windows, 32-bit x86 architecture)

*Provides Visual C++-compatible .lib and MingW-compatiple .a link
libraries. Python and Java bindings for Windows are not included,
but will be forthcoming in the next release. This is the first release
supporting Microsoft Windows; please report any difficulties.
Includes liblo-7.dll and necessary header files compiled from a recent checkout of liblo's repository. Binaries: Python 2.6*
(Windows, 32-bit x86 architecture)

*Includes statically-linked libmapper and liblo. Copy site-packages contents into your Python 2.6 path. Graphical User Interface
(Max OSX)
mapperGUI-2.6.1.dmg Graphical User Interface
(Mac OSX)
mapper-0.3.1-osx-max.dmg Binaries: External objects and documentation for MaxMSP
(Mac OSX 32-bit Universal)
mapper-0.2-osx-pd.dmg Binaries: External objects and documentation for PureData
(Mac OSX 32/64-bit Universal) Binaries: External objects and documentation for PureData
(Windows 32-bit)