"For" can mean "because", especially in texts written in literary style:
Yet this abundant issue seemed to me
But hope of orphans, and unfathered fruit;
For summer and his pleasures wait on thee,
And, thou away, the very birds are mute.
Because, no matter where we look, there is some work to be done.
This sentence justifies a previously made statement. From the full text of Obama's speech:
Starting today, we must pick ourselves up, dust ourselves off, and begin again the work of remaking America. For ("because") everywhere we look, there is work to be done.
We must pick ourselves up and begin with the work, because there is some work to be done in all directions.