With 'Playlist' you don't upload... it's like a mp3 search engine basically. You type a name of a song or an artist into its search and it crawls the web bringing back the potentials... very accurate actually. Usually it brings back multiple sources where the song is, depending on its popularity (like the more that have that song you're looking for hosted on their site... the more sources you have to choose from to get your song from)
You do have to pick one song by one song... except none of time is spent in uploading... since you're getting the mp3 from someone that already hosts it.
Your playlist is then turned into flash which you can embed anywhere where it's allowed. Your own website, a social networking site, what have you. Or you could simple just copy and paste your playlist URL to use the linking method as an alternative... which links to your personal playlist page.
www.playlist.com if you wanna try it.