Good one, worked exactly like it should for me.
For the people that don't see the dots disappearing, just focus straight on the black cross. Don't even think about blinking or you'll see the dots again. They disappeared for me after mere seconds.
Got a good optical illusion here as well:
http://www.d-are.nl/upload/1/illusion.jpg
yes it seems odd, but save the image, open it in Paint, then select the colours of both squares. They are the same.
Or, erase everything out the image except the two squares. You'll see the B square getting darker
Proof (spoiler

)
http://www.d-are.nl/upload/1/bewijs.JPG
it really really looks weird. Cool stuff tho