Collaborative tools. A very simple example: the CorEdux Project (click on the «Invitado» button).

The mail + robot solution: the Free Translation Project

Hi!  I am the service robot at the Translation Project, and was awakened
by your submission for `kbd-1.12.es.po'.

Your file has been accepted and uploaded into the archives:
congratulations! Whenever the maintainer of `kbd' will communicate a
new PO Template file to the Translation Project, the translation you
just achieved will probably require revision.  Your team will then be
notified of the URL of the PO file to revise, with a quick evaluation
of the extent of the work needed.
To speed things up, I could send you updated copies of this PO file by
email, whenever I upload new PO Template files for it.  If you are
interested in this service, you may register by emailing to the
translation coordinator.
                                The Translation Project robot, in the
                                name of your kind translation coordinator.
                                mailto:translation@iro.umontreal.ca
	  

Freeduc-doc Translation Table

Gnome coordination and statistics

Web: Ubuntu's Rosetta (non-free)

KDE's kartouche

Web interface: Pootle (PO-based Online Translation / Localization Engine)