When I try to insert an image using the upload tool, I get:
I'm running the current version of Chrome on Windows, with a number of SE-related user-scripts. Confirmed by several other users, so not just me.
Yep, looks like a problem with uploads to stack.imgur.com -- we've contacted them via email and phone, and have disabled uploading for now until they can get it fixed.
edit: looks like they fixed it, so we're re-enabling uploads now.
Failing for me as well...
-- I used the actual imgur website to upload this image :D