Siri seems to be unavailable for a whole load of people in the UK right now. Looking at a lot of forums including Vodafone, avforums, and other private ones with people complaining of non functionality. Called a load of friends up and they also confirmed it's not working on their 4s' or 5's. Might just be too much traffic on the server? Thought I'd post it here anyway, since this is the first place I looked.