HiddenHttpMethodFilter currently does not work when handling multipart request, as it relies on request.getParameter(..) which does not return the actual parameter's value in multipart requests.
As I can understand that one might want to keep the filter independent of Spring MVC, I'd suggest to introduce a subclass that might lookup a configured multipartResolver from the application context and use it to obtain the parameters. As we deal with a filter this would require the resolver being declared inside the ApplicationContext loaded by the ContextLoaderListener. This feels a little ugly as one probably should tend to avoid web things inside this ApplicationContext.
As the only existing implementation is CommonsMultipartResolver and this implementation uses a static method of ServletFileUpload a reasonable way might also be just to check the availablity of Commons Fileupload in the classpath and using this method to determine the multipart nature of the request then.