It appears the Games Workshop site has been going through outages in various countries at different times. I base this off of the emails I have been getting, but only once was the US site down for a few minutes when I physically checked.
Perhaps there are updates going on right now regarding the magazine changes to White Dwarf and Warhammer Visions.
So if you notice the Games Workshop site down, please let us know here in the comments. No need to report that it is up.
This way we can see if there are changes or updates to the site. Otherwise it could very well be simply maintenance.