Note: this post/site will likely be up and down today - it's getting much more traffic than usual and high traffic seems to trigger some kind of httpd leak on my server, which exhausts the RAM. I almost never get high traffic so I don't really care enough to investigate and fix that; I just let it go. I'll restart httpd every so often to clear things. News sites, if you want to cover this story, probably a good idea to excerpt my post extensively: I hereby place this post under CC BY to allow you to do so. Please at least include all the references I cite so I don't have to re-type them in comments.
I've been trying to keep my cool regarding this whole Mir kerfuffle, but some stuff really gets my goat.
To keep this short and to the point:
Mark's comment is dated 2013-03-10 4:33 PM, if it is not removed: it does not appear possible to link directly to a comment on Google+. Text of Mark's comment: "nonsense. Unity existed before Gnome Shell. And the design of Unity was clear up front, it's Red Hat's team that wandered all over the place before shifting to a design that bears a startling resemblance to Unity." Mark, 'initial stable release' is a largely arbitrary milestone, and not what developers mean when they say 'exist'. GNOME Shell was in existence, under active public development, and being used on people's desktops before Unity got its first commit. Muddying the waters by saying Shell changed its UI is irrelevant: it was very clearly a single continuous project throughout. I know, because I was running it the whole time.
Edit: as a supplemental reference, here is a video uploaded 2009-05-13 showing GNOME Shell compiled from git by a third party, with the top panel - complete with 'Activities', notification area at top right, user menu at top right, and a full screen overview triggered by moving the mouse to top-left with applications down the left hand side and a display of workspaces and windows taking up the rest of the space. If that's not GNOME Shell, I am a hippopotamus. The first commit to the Unity repository is dated 2009-10-15: five months earlier, Shell was in a state where someone who is not part of GNOME at all could check it out of git, build it, run it, and see something that is clearly an early version of the Shell that exists today.
Edit: please, no-one cite the dates given on Wikipedia. Those are the dates of the first official stable release. Mark explicitly used the word existed, in a context which made it clear we were talking about the early gestation of both projects, not their stable release dates. Linus released the Linux source code in April 1991 and version 0.01 in September 1991, but did not release 1.0.0 until 1994: it would be absurd to suggest that Linux 'didn't exist' until 1994.
Mark, please stop claiming you "innovated when we created Ubuntu on a six month cadence". You did not.
Mandriva was on a six month release cycle from the release of 8.0 or 8.1 (in 2001) to the release of 2010 (in 2009), with the sole exception of an experiment with a 12 month cycle between the releases of 2006 and 2007. Various release were early or late by <1 month, but it was a consistent cycle with releases targeted for March and September each year.
Edit: as supplemental references, here I am in September 2003 - long before I worked for Mandriva - writing "Mandrake is released every six months". And here is someone else, in January 2004, writing "Mandrake's Cooker, the perpetual-work-in-progress distro that becomes the next final release of Mandrake every six months or so".
You make these claims regularly, despite them being debunked multiple times in the past. Please stop.