Is there a web service for RDF validation?

Hi all,

A pretty straight-forward question from a newbie to this field: are
there any web-services available for doing RDF validation?

By web-service I mean something with a proper web-service API: e.g.
REST or SOAP, which you could easily call from within your own
application.

Of course I've seen http://www.w3.org/RDF/Validator/ and
http://www.rdfabout.com/demo/validator/ , but they don't have
REST-like interfaces and also seem quite out-of date with respect to
input formats (e.g. no trig). Also, named graph support would be great
to have.

Given the advanced state of development of RDF tools like Jena /
Sesame it seems a web-service should be available somewhere... or is
it time to build something like that myself? Any pointers greatly
appreciated!

Cheers,
Mark