The US attacked the Taliban in Pakistan "for the first time" today, by sending in commandoes with a helicopter. This probably isn't the first time the US has gone into Pakistan, but the first time they have done so without disguise or cover-up.
The village they attacked was less than a mile from the Afghani border, and a Taliban "stronghold;" a clear sign that the Taliban have such free reign in Pakistan that they mostly just camp out on the other side of the border and call the Americans' mothers names.
This was not a NATO operation, which is important: NATO can easily claim no knowledge of the incident, while the US can continue to ride on its bad reputation and say "we don't care," should anyone (the Pakistanis in particular) decide to complain. While NATO must keep a good reputation, the US doesn't have one to uphold at this point.
It's also a sign that the US is not taking my advice (in gathering the Afghanis and Indians into a coalition to threaten to invade) and just making it clear that it can enter and leave Pakistan as it pleases. The weak and squabbling Pakistani government is little-equipped to do much about it unless it does want a full-scale invasion; its political will at the moment is too weakened by domestic trouble.
Then again, given that it's less than a mile from the border, it could actually be an honest mistake.