I assume most people on HN don't know whats going on so I'll chip in what I know:
The admin, allegedly this Thomas guy, ran off with 17k BTC which is worth around $15M right now. Nobody is able to transfer their bitcoin out of sheep either. Everybody is pissed off so people are attacking his server and trying to "dox" the person. Here is the address where the money has gone:
https://blockchain.info/address/1Cwb33nqn4S2uDsXwhNrUNy7FPdi...
If anybody is interested, check out the sheep subreddit, lot's more information on the issue there.