Hi Ben Friedman,
As I can see, you have all the necessary assemblies in the bin. However, it seems that the .Net Assembly Loader is unable to find the right assembly (with the requested version) but it finds an assembly with different version. Please check if the web.config file has a reference to the mysql.data.dll library that specifies particular version to be used. If there is such reference, you can try removing it, this way the dll from the bin directory will be used instead of the installed one in the GAC.
the Telerik team