Bitcoin-trader.biz is the other arbitrage site and I'd say they are doing vastly better with PR than btc-arbs.  Arbitrage isn't a scam, it is real, it's just the players doing it that could be or could not be legitimate.  In the future I can see more arbitrage services popping up and the exchange prices will eventually get closer together more quickly.

That's why arbitrage requires very fast computers and Internet connections on Wall Street... there are a lot of people fighting for the arbitrage rate and the fastest computers get the transaction.  In Bitcoin this isn't so, you see the exchange rate way different on Bitstamp/BTC-E all the time.