Red Hat's Adam Williamson, among other open-source developers, are ticked off by some of Mark Shuttleworth's recent claims regarding Ubuntu. It's just not about Mir, but other topics too. The Fedora QA manager wrote a personal blog post today entitled Dear Mark Shuttleworth: please tell the truth.
One of the most recent controversial claims is that Canonical's Unity desktop came before the GNOME Shell. Shuttleworth wrote as a comment on Google+, "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."
Williamson makes reference to a post that the GNOME User Experience Hackfest in late 2008 is where the GNOME Shell concepts were born. It wasn't until 2009 that things heated up within Canonical about persistent notifications and their Ayatana project where they began deviating more from upstream GNOME.
For some other timeline perspectives, the initial release of Ubuntu Unity happened in June of 2010 while the initial GNOME Shell release was in April of 2011, which may be what Shuttleworth is referencing in terms of initial releases but not when development began.
It wasn't until the Ubuntu 11.04 release in April of 2011 where Unity became the default desktop experience. It was in October of 2010 when those plans were shared. Meanwhile, for another reference point, "GNOME Shell" has been talked about on Phoronix since mid-2009 with its development releases.
Adam also picks on Shuttleworth's claims about it being Canonical's "innovation" to have a six-month release cadence when Mandriva/Mandrake was on a similar cadence long before Ubuntu even existed. Other Linux distributions have also done bi-annual release schedules too.