Codenamed "Oneiric Ocelot", this version was released on Oct 13, 2011 and is no longer supported since May 9, 2013. Questions about unsupported versions are likely to be closed as off-topic.
Oneiric Ocelot was released on 13 October, 2011, and was supported till 9th May, 2013.
Code name: Oneiric Ocelot
Ubuntu Flavors available under 11.10 (questions on all are allowed):
The 11.10 Ubuntu variants - Mythbuntu, Ubuntu Studio, Xubuntu, Lubuntu - are not commercially supported by Canonical.
Ubuntu Editions available under 11.10 (questions on all are allowed):
Questions on are considered off-topic since it had reached the end of life.