Starting 2013 DB German Rail will connect London Paddington with Amsterdam, Rotterdam, Brussels, Cologne and Frankfurt (Airport and Hauptbahnhof) via ICE bullet-train service. Details and a Video here: http://www.breakingtravelnews.com/news/article/deutsche-bahn-outlines-international-plans/?utm_source=newsletter&utm_medium=email&utm_campaign=newsletter
I prefer to wait a little more. There is a fuss about whether the DB rolling stock meets the Channel Tunnel safety standards and they need to put pre-clearance immigration and customs UK facilities in Frankfurt.
I'm not surprised at the London-Brussels-Cologen/Frankfurt connection. German Rail has had a discounted Europa-Spezial fare, using ICEs to Brussels and Eurostar from there to London. This just eliminates the change of trains in Brussels. However, I would be surprised if German Rail is carrying passengers from Brussels directly to Amsterdam and Rotterdam. Maybe they go via Cologne. There is already ICE service from Cologne to Amsterdam.