J.K. Rowling's official website has posted the third and final WOMBAT test!
Here are the access instructions from the Harry Potter Lexicon:
1)Click on the pink eraser to get to the room with the locked door.
To open the Door and activate the WOMBAT:
2) Click on the fly that lands on the window, it will turn into a key,
3) Drag it to the lock and let go, the key will turn and the door will open.
4) Drag the ring onto the rod, it will sparkle if placed correctly.
5) Drag the triangle onto the rod and ring, it will sparkle and move to the desk.
6) Click on the WOMBAT paper to open the test.
Good luck to everyone!