I'm not sure of actual stuff, but in theorty, the city has been pushing (on many fronts) for a westward expansion of the Loop since it seems like day one (Sears Tower was trying to promote westward office development, no?)
The circle line and the now "pink" line (phase 1 of the circle line) are attempts at solidifying westward transit connectivity. The near west has really good infrastructure anyway (look at highway maps and transit maps), but these are pushes towards the west.
There has been alot of construction activity west of the loop. I think the one that created the most buzz was Skybridge (which never ceases to amaze me when I drive past on the way to the airport or something). Alot of smaller office buildings have been going on, and it doesn't help that there's been a whole of building activity near the UiC.
However, as for actual skyscrapers... I think it'll be a long time before we get anythign remotely like the South Loop going on there. The river is just way too much of a psychological divide currently. And location matters hugely. The difference between being in the loop versus west of the loop is very significant.