I like the idea. Too bad it doesn't work on my iPad. It's hard enough carrying a cello around on the subway, so I'd prefer not to carry a whole laptop.
Actually the website should work on the ipad for everything except the sheet music display: that means if you want to play the full orchestra accompaniment on your iphone or ipad, you should be able to do it.
The music scores display uses the Scribd API. Scribd is currently switching from flash to html5. The full app should be 100% available on the ipad in the next few weeks / months.
Of course, we are also planning on developing a more specific version for easier navigation on mobile devices.