I have had a look around on their website and elsewhere. It has been three years since the last blog posting (February 5th, 2013) when version 2.5 of GeoKettle was announced.
The mailing list for developers on sourceforge.net does not have any entries after December 2012. The mailing list for english speaking users had its last entry in september 2014. Last update on the french user mailing list on sourceforge.net was in august 2011. Their website forum seems to be down.
Download of the project from Spatialytics market seems to have been discontinued. Downloads are however available on sourceforge.net with the latest update prepared the 20th of April 2015.
Found a mirror of the GeoKettel 2.0 code on Github with user icholy. He could however inform me he is no longer using the system. The website has some info on trac related to version 2.6, but it seems to stop there.
https://gis.stackexchange.com/questions/tagged/geokettle suggests that the system is still in use by someone.
To me it looks like the project for some reason has been abandoned, but I will update this answer in case I hear otherwise.