Software Frameworks

Today

On top of your parser? While XML Schemas is in many ways a replacement for DTDs, it isn't integrated tightly with XML 1.0. Developers who want to add schema functionality to their products may be adding filters or processing modules that apply schemas to the results of XML processing.
In your parser? An early access edition of the IBM parser integrated an older draft of Schemas. It's likely that some future parsers, from Microsoft and perhaps Apache, will build in this functionality.
Other tools Extensibility is committed to supporting XML Schemas in its editor, but it may be a while before the process is finished.