libmono-dev 2.4.3+dfsg-1ubuntu2 (amd64 binary) in ubuntu lucid

 Header files and static libraries for libmono.
 .
 Mono is a platform for running and developing applications based on the
 ECMA/ISO Standards. Mono is an open source effort led by Novell.
 Mono provides a complete CLR (Common Language Runtime) including compiler and
 runtime, which can produce and execute CIL (Common Intermediate Language)
 bytecode (aka assemblies), and a class library.