Marlin (which according to ammonkey, the lead developer, is "no longer an elementary app" but of course, that doesn't mean it won't be a part of elementary OS), got Unity progress bar support thanks to a patch by Marco Trevisan. Along with Unity progress bar, Marlin also got dynamic quicklists that allow you to show the copy dialog or cancel in-progress actions.
Since Marlin is no longer a part of the elementary project, it's not available in the elementary os daily PPA anymore and it now has its own daily PPA. Add the Marlin daily PPA and install it in Ubuntu 11.10 Oneiric Ocelot or 12.04 Precise Pangolin using the following commands:
sudo add-apt-repository ppa:marlin-devs/marlin-daily sudo apt-get update sudo apt-get install marlin
To also install the Dropbox and Ubuntu One plugins, use the following command:
sudo apt-get install marlin-plugin-dropbox marlin-plugin-ubuntuone
Report any bugs you may find @ Launchpad.