A while back I was looking for an open source Music Notation/Composition Program. I found Lilypond, which is all text based. I was going to work on making it portable, but it's not that beneficial to most users. There are about three GUI's for Lilypond, but only one has Windows binaries, and it's not so great. It also hasn't been updated in a while.
So today I found a program that's still in fairly early developement, Canorus. The development's been pretty constant, and it's coming along pretty well. It still doesn't have a lot of features people expect coming from programs like Sibelius and Finale, but it's got the standards to write a decent piece of music.
So, although it's still in development, I was wondering who would be interested is I worked on a beta and posted it within perhaps a week/two? Only respond if you're actually interested.
Thanks, please check it out and post back.
Edit: By the way, take a look at the Roadmap, there's no crucial features coming that most end-users would be interested in before the Final Release.