An email from the developer:
Piano Booster is a new free Open Source Application that makes sight reading music fun. It takes elements of the game Guitar Hero but now it uses a real Piano Keyboard and the game has been turned sideways so the notes scroll along a musical stave. So instead of pressing buttons on a fake guitar you end up learning to play a real musical instrument -- the piano.
To find out what it is all about take a look at the YouTube video:
or look at the screen shot:

First choose a MIDI file then select the "left" hand or the "right" hand or if you are feeling really brave choose "both hands" and try to play along. The "Follow You" mode make it really easy to sight read the scrolling notes as the whole accompaniment will stop and wait for you to find and play the right notes. The accuracy bar monitors how well you are playing.
The software is available for free (Open Source GPL) for both Linux and Windows from this site: http://pianobooster.sourceforge.net/