The Obama administration is sending 1,200 National Guard troops to the U.S.-Mexico border, and promising $500 million for border enforcement. The AP reporter sums it up pretty well:
President Barack Obama's plan to send as many as 1,200 National Guard troops to the US-Mexico border appears to be a scaled-down version of the border security approach championed by his predecessor.
Same as with President Bush, the idea is to be seen as "doing something." The hope is that "doing something" will create some momentum for immigration reform by "securing" the border first. Already, the Obama administration is deporting more people a year than Bush.
But that will not happen, because the goalposts will consistently move. Already, John McCain has said he wants far more troops. Since it is not actually possible to "secure" the border, there will always be calls to spend more on enforcement.
Meanwhile, the Mexican government issued an official statement in response, arguing that the troops should be used to stop the weapons and cash going into Mexico rather than immigrants coming out of it.