For this I downloaded Soundcloud, and from what it sounds like, Soundcloud is well on its way to being the Youtube of mobile audio. There is a massive user base uploading music, spoken word, podcasts and other sound programs to Soundcloud. Browsing around on it, it seems like some libraries are hosting archived audio from speakers that they had in the past. Other schools and libraries have put up lectures and talks. Music libraries are very prevalent, hosting their collections on Soundcloud so a wider audience can browse their holdings.
I like how Soundcloud separates Audio from Music, you can browse things like podcasts, lectures and talks just as easily as music without sorting through them yourself. Soundcloud is a freemium service, you get 120 minutes of audio on a free account, but once you pay for an account your cap is lifted. Like Youtube, Soundcloud allows you to follow different users, see what they are uploading and what they like, and have fully embraced the social aspects of web 2.0.