Holy crap. Someone on Reddit (I think he’s also on KYM…his username is Nintendork64) thought up an amazing theory on what these items will do. He said, and I quote:
“You don’t suppose this will be a Multi-part update, do you?
Day 1: Damaged Capacitor. Happens on 6/22, 15:00. The Mann Vs. Machine mode arrives.
Day 2: Pocket Lint. Hats and clothes for the various classes? Maybe some Sherlock Holmes/mystery based stuff?
Day 3: Banana Peel. A Grortbort set comes out, tying into the transcript, and including the helmet mentioned in it.
Day 4: Barn Door Plank. A new barn or countryside-based map is released, one which involves horses (as mentioned in the barn door plank description)
Day 5: Cheese Wheel. Steam and TF2 come out for Linux (Cheese is a Linux-only program).
Day 6: Goldfish. The 2nd annual Saxxy Awards are released, the missing Australium from the story is found.
Day 7: Secret Diary. Meet the Pyro is finally released. In it, we see the Pyro looking through his/her diary and the story is told through corresponding flashbacks of the Pyro’s life and how s/he became obsessed with pyrotechnics.
This is all wild speculation, of course, but these items must have some connection… Plus, there are 7 items, one for each day of the week."