I know this has been brought up before, but I wanted to put my vote in for this actually happening. I understand that there is a widget for server-hosted WordPress sites, but nothing that I have found for WordPress.com hosted blog sites.
It would be a really nice feature and one I would get a lot of use out of (I have a huge text document of random quotes I can't put to use anywhere!). So, if it's been put on the back burner or decided against, please reconsider! Thanks!