...For newest binary builds, look in the "/bin" directory of the Subversion distribution (code section).
Make sure to also download the 2008 version of math.dotnet.iridium. The corresponding dll file is in the files section.
...Ceme is a free math expression parser library written in C# supporting various operators and functions. It also has the option of adding your own functions. A wrapper DLL is provided for non .NET applications.