On April 21, 2001, the Electronic Frontier Foundation released v1.0 of their open audio license. The license allows anyone to copy, modify and distibute music free of royalty, as long as credit is given to the original artist. This is good for new musicians not very well known trying to get their music heard.
Having to clear samples from other songs would not be necessary (assuming the original song is released under this license).
The idea is that music is not intellectual property, and should not be owned by anyone. It's yet to be seen whether this open license idea will work as well for music as it has for free software, but I believe it will. The text of the license is at http://www.eff.org/IP/Open_licenses/20010421_eff_oal_1.0.html. And I like how the symbol used is (O) (for open), the (C) just seems like an incomplete circle compared.