It’s not perfect. Pidgin’s MeanWhile doesn’t handle logged in users properly.
To fix that on Ubuntu, go here, and download the package for your install – 32-bit or 64-bit. Then execute
sudo dpkg -i libmeanwhile1-1.0.2-3*
… and restart Pidgin. You may need to hold or lock the libmeanwhile package from an update.
There’s an outstanding issue about file transfers that still requires a solution.