I just came from their site and read their message, saying they have shut down their site. You can read the message here.
Unfortunately if you had Superpoints on the site and didn't cash out before 3pm today...your points are now gone.
That really is unfair to a lot of people I've heard from that had what amounts to $90, $100, $150 or really any amount. Thankfully I cashed out my last $5 Amazon gift card last week, but I feel bad for those who had hundreads even thousands of points on the site and now have lost them all.