In addition to cleanup of all the bricks, dust and other debris that was left over from last week's demolition of the outer bleacher walls, the Cubs had crews in the triangle lot starting to take the concrete panels off the outside walls of Wrigley Field on the west (Clark Street) side of the ballpark.
That's the first photo in this gallery, the one I took myself (and there are more of this work later in the gallery). The rest are from David Sameshima, showing the cleanup work that's going on, on both sides of the bleachers on Waveland and Sheffield.
My understanding is that the demolition of the steel superstructure and concrete bases to the seating area will be next. If you are familiar with the bleachers, you know that there are stairwells from the upper to the lower level on both sides, that are in what you'd probably call "deep" right-center and left-center field. The demolition will be to the left (in left field) and to the right (in right field) of these stairwells; everything else will be left as is. Also, the metal gates that surrounded the bleacher entrance have now been removed, so there's nothing really left underneath the superstructure at all.
As you can also see in some of the photos, some turf was removed from the field as well today.
Beyond that, the photos should be pretty self-explanatory.