It's taken a long time, but the new version of Poligo is live!
Most of the site is basically the same. The only big difference is the system for comparing your writing to the teacher's. When you check your writing, you will only see a corrected, 'clean' version and the comments from your teacher. If you want to see your mistakes, you will have to use the 'Revisions' tab above your writing. The help page explains it in more detail.
If you find any bugs, strange Japanese, bad formatting or anything else, please use the feedback tab on the right of every screen.
If you want to access the old Poligo to check your writing from before, please go to http://old.poligo.com. There is also a link at the bottom of My Page.
Let me know what you think of the new site in the comments.