Ubuntu for tablets is, like Ubuntu for smartphones, based on Ubuntu Touch which lays heavy emphasis on gesture-based use and removing all soft and hard keys. Much like the new Blackberry 10 the edges of the screen drives the navigation of the operating system and is the principal means user input.
Mark Shuttleworth highlighted a new feature called Sidestage. This allows the user to run tablet and phone apps side by side on the tablet, sharing screen real estate also allowing the user to resize the panes when needed.
In keeping with the design of the Ubuntu desktop OS, the tablet version also incorporates scopes and lenses, the dash and left side launcher panel. Also in the tablet OS is the HUD which will be voice driven, possibly targeting apps Apple's Siri.
No hardware vendors or carriers have been confirmed to partner with Canonical to pre-install Ubuntu OS on either tablets or phones currently.
Note: Previous speculation that Ubuntu and HTC would be partnering to release a tablet has been disproved as HTC released the HTC One smartphone today, coincidentally at the same time as Canonical's release of the Ubuntu Tablet OS