iOS 5 Music App Grey circle with a square inside it next to the song title - what does it indicate?

I had a few problems downloading a few tracks from the iTunes store direct to my phone. As a result I seem to have placeholder versions of the songs that will let me stream them but not play them.

In the library they have a grey icon next to the song titles a circle with a small square inside, very much like a stop icon but it seems to do nothing.

What is this icon and what does it indicate?

The screenshot shows the problem tracks with icon and the ones that have synced over from iTunes (which are "normal").

I do use iCloud and have music automatically download, I don't have Match.

The name of the artist and my name being the same is just a co-incidence.

Well, that symbol is the download progress indicator. It appears when you buy a song from the iTunes Store directly on your device. The progress is shown in a bar that goes around the circular track on the outside.

It means that it can be listened to via streaming (by clicking on it in the normal manner) if you have a suitable internet connection but has not yet been downloaded to the device.