What is the current legal situation of online poker in the United States?
The short answer is that, with a few exceptions, no one knows for sure.
At the Federal level there is no law that specifically addresses online poker. For many years now the DOJ and the FBI have maintained that the Federal law known has the WIRE ACT makes online poker illegal. This law, however, has been held by two Federal Courts of Appeal to apply only to sports betting. Also, the WIRE ACT itself only criminalizes the provider of the "gambling" service, not the individual bettor. Until and unless the US Supreme Court takes a case and overturns the decisions of these Courts of Appeal, it is therefore safe to conclude that no Federal law makes online poker illegal.
In the US, however, citizens are also subject to state law. A few states specifically make playing online poker illegal. Although no one has yet to be arrested under any such law, if you play online poker from one of those states, it is a crime.
Most state laws say nothing about playing online or about poker specifically. Virtually all states have laws against "gambling" outside of licensed Brick and Mortar casinos. Most states define gambling as wagering on a game of chance. A game of chance is usually defined as a game where the outcome is more dependent on chance than on skill. That is still an open legal question in most states, as is whether these general anti-gambling laws apply to the internet.
Further complicating the answer, in the fall of 2006, the United States passed legislation that significantly altered the landscape in the online poker arena. The SAFE Port Act included legislative language commonly referred to the Unlawful Internet Gambling Enforcement Act (UIEGA).
This law focused on halting the electronic transfer of money to gambling sites in relation to unlawful Internet gambling. It did not define "unlawful internet gambling" in any new way, however, instead it said unlawful internet gambling is that which was already illegal under any state or federal law. Subsequently, Party Poker withdrew from the United States market, as did many other smaller poker sites. Major electronic financial service companies such as Neteller found themselves in the middle of this and also withdrew from the market.
The legislation did nothing to change the status of internet poker players and did not focus any of its efforts on penalizing or criminalizing players. Rather, the measures focused on those companies that choose to accept and process financial transactions that are deemed related to illegal internet gambling.
Several major sites still allow United States players to play and there are methods for getting money into and out of these sites. Whether a site that only offers poker, and whether a money transfer to sites that only offer poker, are breaking this new law is a hotly debated question, and the answer depends on a lot of other questions involving individual state laws, foreign treaties, interstate commerce, and other issues.
Under the UIGEA, the United States has also issued additional regulations relating to this law. On October 1, 2007, the proposed regulations were published and open for comment. A discussion of the proposed regulations can be found here.
Throughout this forum you will find threads and posts discussing the ongoing debate over online poker's legal status. Until the Courts rule, or new legislation passes, however, the answer will remain (except in those few states where its a listed criminal offense) no one knows for certain.