http://blockend.net/To enter simply send any amount of bitcoins to the address shown and you are entered. When the target block is mined the round is over and after several more blocks have been mined to account for orphan blocks the winner will be determined and paid.
Winner is found simply by matching the last character of the block hash to the last character a transaction hash in case of a tie funds are split based upon ratio of initial amount entered. We are currently running Round 3 with a target block of 235,000.
All coin winnings will be sent to the address sending in the coins to us. Do not use a shared wallet, Mt.gox etc.
As to the trustworthiness all transactions are open on the blockchain including the winner selection and proof of winner receiving payment. No hot wallets exist on the webserver fronting the page to remove the possibility of a hacker compromising the server and stealing the coins. In other words all coin handling is managed elsewhere.
Additionally if you are afraid I may hit and run with some coins send a few satoshi over, nothing big lost, however nothing really gained either...
In any case, it is better to earn coins legitimately and in the long run more can be done than making a one-time disposable scam.
Feedback, Questions, Concerns?