It's wonderful to hear that you have an interest in streaming music! Did you know that your great-great-great-grandfather Henri subscribed to a streaming music service in 1892?
Unfortunately, Amazon has not released an API for its new Cloud service. Nor did Amazon Web Services (AWS) reply to TUAW when pinged about any upcoming plans for developing such a feature.
But those wild and crazy AWS fans didn't let that stop them. Auntie tracked down a very promising discussion thread over at the AWS forums. Looks like Cloud, which is built on Amazon's S3 storage-in-the-clouds service, uses the same API calls as S3 does. Some enterprising developers have put together a Python-based set of scripts that offers a third-party library to access your Amazon Cloud Drive.
Coding on this project hasn't quite finished yet, and Auntie hasn't found any OS X developers yet who are working on client software to integrate your iTunes media with Cloud storage (ping me if you are working on this!), but hey, it looks like all the major technological roadblocks have been leveled, and it's just a matter of effort to go from point A to point B now.
So can you upload playlists directly from iTunes to Cloud? No. Not yet. Possibly not ever. (Especially since Apple seems poised to move into this space on its own.) But with third-party support? It looks like it's just a matter of time.