What ways can a web developer stream audio to a web user (without Windows Media Player or Flash)?

I’ve developed web browser applications that play sound and video before but I’ve always used the Windows Media Player ActiveX control or Flash, and either non-streamed content, or the Windows Multimedia server. Now I’m researching an audio project which would like to work on Linux, Macs and iPhones, which I believe excludes using WMP or Flash.
Do IE/Firefox/Opera support playing audio streams via JavaScript calls these days? Or is a plugin/control needed?
Is QuickTime the way to go? Are there other solutions that come to mind?
Thanks!