I just uploaded five new images tonight and for four of those images I got the new version of the upload page, but for one of them, it gave me the old version of the upload page without everything divided into categories. I have no idea how I got to the old page, but I prefer it greatly over the new one. Does anyone know how I might have stumbled across the old one and how I can continue to use it in the future?

You probably stumbled upon the "compact" version of the upload page. Apparently there's some obscure button that takes you there optionally?
Anyway you can enable it normally by going to Settings -> Advanced -> Enable Compact Uploader: Yes

donteven said:
You probably stumbled upon the "compact" version of the upload page. Apparently there's some obscure button that takes you there optionally?
Anyway you can enable it normally by going to Settings -> Advanced -> Enable Compact Uploader: Yes

Perfect, thank you!