Here's a picture near the top of the switchbacks, taken April 28. These hikers are NOT taking the switchbacks, since they are completely snowed in at this time. Instead, they're going straight up the snow slope, sometimes called the chute, just west of the switchbacks.
This picture from the set posted by gocarine on Flickr here: Whitney 4/27/12
This picture of the first stream crossing (North Fork Lone Pine Creek) where the Mountaineers Route branches off the main trail. Taken by Bob R on April 21. From his 2012 North Fork picture set.