To support the OASIS genericode XML format for code lists (version 1.0 is currently on public review), I have started writing an open-source validator (called "gcv") for genericode XML files. Part of the validation is XML Schema validation.
I'm starting with a C# implementation for .NET and Mono, and I currently plan to port the code to Java once I'm happy with the C# implementation. For those of you who aren't aware of Mono, it is an open-source, cross-platform implementation of the .NET technologies that Microsoft has standardised via ECMA. Mono gives .NET some much-needed cross-platform credibility.
Unfortunately, the Mono XML libraries appear to have some bugs around Schema validation. Today I posted bug #82010, which demonstrates that Mono 1.1.18.1 and 1.2.4 both give different Schema validation results to .NET 2.0 (and other Schema validators) when validating a genericode example. What this means is that my genericode validator won't run under Mono until such time as this bug is resolved. That's a pity; we'll just have to see how long it takes to get it resolved.