PyShare 0.6.1 is a handy script that allows you to upload files (screenshots, images, etc) to IM, Forums, Direct, Forums Thumbnail, Html Thumbnail and Twitter, etc.
Installation process is quite easy, download the archive, unpack it, run install.sh and install python-pycurl and scrot (dependencies)
sudo apt-get install python-pycurl scrot
To start PyShare, right-click on a file in nautilus and choose: