Bitcoin exchanges like btc-e are becoming more popular, however they still do have there glitches, latency ect. Also, I wouldn't keep too much money at any one place due to the risk of the place going belly up or whatever else.
Arbing between exchanges can be difficult due to the time it takes to move usd around. Exchanges don't have that great of matching algos yet and during heavy vol it really bogs down at most places.
In other words, you will need to wait a while until there is anything as stable in the bitcoin world as there currently is in the fx, usd trading world.
IMO if you want to participate in bitcoin, coinbase.com is the best way for the avg joe to buy the coinsand get involved on the upside potential. For selling, or trading with other currencies, there is another forum in the bitcoin section that tells you places you can trade.
Currently I'd imagine if one is trying to use stop losses and that type of trading , you will get heavy slippage because these coins don't have that much volume yet.