Although I've written about it in the past (when it was at 3.6 version) but according to the developers themselves you should consider upgrading to the latest version (4) since it brigs major improvements/features when considering its predecessors.
Few of the noticeable "enhancements"...
*. Sync multimedia files with Android devices.
*. Android and Amazon MP3 store support.
*. Unity's appindicator integration.
*. Share files in any PC/Laptop that has Miro installed (over the network as well) - DHT support.
*. Shuffle/Repeat playback options.
*. Watched/unwatched "filter" for video feeds.
*. New volume slider (only for Mac OSX).
*. Important media option added.
These are just a few of the main features to mention. So, if you want to install the Miro version 4 in Ubuntu 11.04 Natty Narwhal, then open your Terminal and enter the below command.
sudo add-apt-repository ppa:pcf/miro-releases
sudo apt-get update
sudo apt-get install miro