The New York Times reports this morning that three American soldiers were killed and two were wounded in Pakistan. Their deaths were the result of a remotely detonated roadside bomb in a village near the Taliban-ridden Swat Valley. The military says that the soldiers were in the area training Pakistani paramilitary forces. The NYT says that the Pentagon has acknowledged that the U.S. military has sent advisers to Pakistan in a consulting role, but this article insinuates that this is the first time that U.S. soldiers were killed inside Pakistan while on a mission.
I think this article confirms what most people knew was a virtual certainty: that U.S. military forces are operating inside Pakistan. I also assume that these aren't the first U.S. military casualties inside Pakistan, but they are the first that we are hearing about. I think it highly likely that these soldiers were members of U.S. Army Special Forces who played, and continue to play, a major role in Afghanistan. The primary mission of Special Forces soldiers is what is called "foreign internal defense", which is essentially training groups of indigenous forces in a country to fight. This is a major component of the mission in Afghanistan as well as Iraq. Based on what the NYT article says these soldiers may have been a "training unit" attached to Pakistani paramilitary forces. That sounds like it is right up the Special Forces' alley.
I don't think that this incident is any kind of harbinger to escalated U.S. presence in Pakistan. There is virtually no chance we get heavily involved in Pakistan in the sense of having a military presence there. President Obama has made it clear that the goal is to get Afghanistan in some form of stability as quickly as possible and get out of there so that he can redirect that money towards fixing domestic issues. Since that is the goal I don't see any chance of us getting involved in Pakistan; however, this story does draw attention to a military presence in Pakistan that is usually downplayed.