With the UIGEA of a few years ago and the shutdown of the 3 largest US serving poker sites earlier this year, the situation for US players is pretty terrible. It currently takes 2 weeks - 2 months or more to cash out of a poker site and it is very costly and risky for the sites as they risk having payment processors shut down and their funds stolen by the US government. The sites out there could pretty easily use bitcoins as a cashout method without even having to speculate in the price of bitcoins. They could just buy bitcoins on mtgox as a player cashes out while keeping the sites money in mtgox as USD. Being able to cash out players for a <1% fee vs the current cost of 20%+ would be good for the poker site. For the players, being able to quickly receive bitcoins would be a big improvement over the status quo. It seems that these 2 things would give a bitcoin using poker site a huge advantage over the other skins on the network.
Buying a poker skin on an existing network with thousands of players already playing would allow a site that has fast bitcoin cashouts to attract players who cash out frequently and are currently playing on other skins on the network. These players tend to play alot and generate tens of thousands of dollars of rake each year. If a poker site skin had bitcoin cashouts, they would likely have every high volume player who plays on that network playing on their site within a few months. Having your money out of a poker site almost instantly, as would be possible with bitcoins, would turn poker players into bitcoins believers pretty quickly.
Bitcoin deposits could also be accepted and converted to USD by the poker site, but withdrawals are a much bigger issue as high volume players aren't depositing very often and recreational players are less likely to know about bitcoins and be willing to use them.
Obviously a poker site using exclusively bitcoins would be ideal, but there aren't anywhere near enough people willing to play on a bitcoin only site. Integrating bitcoin into an existing USD site would be a pretty big step towards mainstream acceptance of bitcoins, for gambling at least.
Would gox or other exchanges be willing to take the business of a US serving poker site? Seems that this would draw alot of attention from the US govt if bitcoin became the primary way of cashing out and/or depositing onto poker sites for americans.
The largest network that serves US players is Merge @
http://www.mergegaming.com/.