I was actually thinking about doing this. I have the marketing background and could really make something take off. One thing you are going to need is capitol we are talking around $10-50k in bitcoin at least.
You need something cool and different. I think Poker would be really cool with Bitcoin and other currencies.
When I was looking into it there where some issues I am still working out in my head. You are better off making a new currency. Call them Bit Chips, when using bitcoin on the gambling side the huger issue seems to be the transfer rate times.
You need to make cashing out fast and easy, this is a must on a gambling site because well even the popular ones out now are crap.
Another goal is offering like a quick cashout conversion. Where you have a service that will cash out your bit chips to bit coin and almost instantly to the currency they chose.