By default, Gnome does not provide a print option in the right-click menu of the file browser. Luckily it is very easy to add more functions to this menu.

Nautilus will look into the ~/.gnome2/nautilus-scripts folder and add the files it finds there to the 'scripts'-entry in the context menu that pops up whenever your right-click a file.

Create a file called in this folder and paste the following script in it:

# Print files from the right-click context menu in Nautilus.
# Place this script in ~/.gnome2/nautilus-scripts.

# The printer to use (as shown in the Printer Configuration
# gui or in /etc/cups/printers.conf).

        lpr -P "$printer" "$file"
exit 0

Replace "HP-Color-LaserJet-CP1215" with your own printer model. You can find the exact model name in the CUPS printer configuration GUI (Ubuntu: System > Administration > Printing).

Save the file, and make it executable:

$ sudo chmod u+x ~/.gnome2/nautilus-scripts/

From now on you can easily print multiple files directly from the file manager without having to open them first.

Reference: Ubuntu: Printing with a mouse right-click - the inspiration for this article.