I would really like to see IMSLP available as linked data, and integrated with other linked data sources.
Linked data is basically RDF+HTTP, allowing to publish databases on the web and interlink them together.
There is already a RDF vocabulary dealing with such music data, which has been used to interlink a number of music-related datasets.
There is also a dedicated mailing list for all things linked data.
I am really willing to contribute on that, I think I'd just need a database or XML dump to start with.
Cheers, and congratulations for today' announcement

yves