It's official! Baby's First Piano is now in the Windows Store and you can download it here!!!!!!!!!
After my last submission to the store, it actually got rejected again. This time, it was because my app did not meet certification requirement 4.1. You can read about the details of 4.1 here, but it is related to network capability. Since my piano app doesn't actually require an internet connection, by removing the internet capabilities. I then recreated the package and resubmitted it to the store.
Next thing I knew, it was in the Store!!!!!