I think the "Manage > Media Library" page should have a link or a button to upload images.
If I want to upload images for other people to use in their future posts -- or upload something for a future post for myself -- I have to do a kludgy workaround by going through the "create a new post" page. Yecch.
After all, adding files to a media library is a management task, isn't it?
Overall, I really like the look and feel of the new interface (great job!), but this is something that I think got missed.
Thanks for all your hard work!