Apple's iTunes Match service, recently opened to developers, either streams or doesn't stream, depending upon how you interpret things. Confused?
It's all a matter of semantics. An Apple spokesperson, speaking to AllThingsD, denied the service provides actual streaming of music.
"An Apple spokesperson confirms that any music you want to access from your cloud-based 'locker' will still need to be stored on your iPad, or iPhone, or whatever device you’re using to listen to the song."
The question is, what exactly does that mean? For most people, a streaming service means that when you want to play content, you don't have to wait for it to download before it plays. It just starts playing immediately (or fairly immediately, after buffering part of the stream). In other words, if you have to wait for the whole thing to download, it's a download service. Otherwise, it's a streaming service.
In the case of iTunes Match, it's downloading all right ... to a cache. You can either choose to download the entire track to your device, or play it while it downloads to a local cache. Just how big that cache is, Apple probably won't tell us. To be honest, it's really no different that a service that buffers some of the content before playing it; Apple just uses different semantics.
If the cache is large enough, Apple's version of a streaming service may provide a better user experience for the consumer, and that's always Apple's aim: a good user experience. You can view a video of the streaming ... or not streaming ... or streaming plus service, whatever you'd like to call it, below, and make up your own mind.