Click-Lock Available?

I have used various mice, often with their own proprietary software. Many of them have a "click-lock" feature that allows you to choose one or more items and move them as though the mouse button were still down, though it doesn't actually have to be held down. I find this particularly useful in iTunes for moving songs between playlists, but also in other contexts.

I'm now using the new Apple Magic Trackpad. So far as I can tell, it is missing the click-lock feature. Is there any way of activating that feature for the trackpad?

If there isn't, I hope this will be considered as something to be added to the software.