The JWST primary mirror covers are being removed today for a short (2-day) test. This will probably be the only time they are removed before the telescope is folded up for launch in 2018. Here's the live webcam of the cleanroom
at Goddard. Five covers have been removed so far. People in bunny suits dangling precariously over the mirror. Yeeesh! I can't watch :/
The telescope is being tilted up to vertical at this moment and will be flipped like a pancake to a mirrors-down orient ahead of the science instrument package install on the back side. Check the webcam (which is on a 1hr delay). The secondary mirror support is stowed down across the mirror in its launch configuration.
Here's a live stream from the cleanroom viewing gallery
on the Goddard facebook page - face-on to the mirror.
The 180 rotation just took place and should be visible on a 1-hr delay on the cleanroom webcam starting at about 14:40 EDT on the timestamp in the webcam images (3:40 PM EDT in real time). Its possible they might block the webcam partway through this rotation for proprietary reasons, just as they closed the curtains in the gallery.
Here's a time-lapse animation of the flip operation last week: