(2012-10-04) Bernard Vatant: The time line is the one of UMBEL globally, the UMBEL vocabulary being only a part of it. See http://umbel.org/ and http://techwiki.umbel.org/index.php/UMBEL_-_Annex_B for more details.
(2013-12-16) Bernard Vatant: UMBEL has made an impressive effort to provide interlinking and inteoperability of vocabularies, but its adoption in data does not seem to have happened yet.
(2014-07-30) Bernard Vatant: Updated version history from GitHub information. No date in the RDF file, no change of version number since first v1 release.
(2020-08-06) Ghislain Atemezing: Umbel has been retired on the end of 2019(and the domain name has been bought) see https://www.mkbergman.com/2229/umbel-to-be-retired-by-end-of-2019/. The successor seems to be KBpedia at https://github.com/Cognonto/kbpedia