The existing D1 bindings are BSD. Boost would be great, although you seem to have already put the LGPL clause in some of your translated header files.
As I understand it, LGPL comes into play if you want to link statically, alter the source of the library, or distribute the DLLs. AFAIK only if your bindings are GPL/LGPL *and* you distribute the source code then you can distribute the DLLs (libcairo-2.dll and its dependencies libpng14-14.dll and zlib1.dll). Otherwise the user would have to download them (from http://www.gtk.org/download/index.php), or maybe an application installer could do this automatically for its dependencies. I'm not a lawyer though.
