TV as home control center (calendar, emails, weather etc.)

[sbav1]

It's very much doable, you can display whatever you want on top of any TV feed (regardless of the signal source), by writing directly to OSD/overlay framebuffer. Even semi-transparently, if you want it that way. The main limitation is image resolution (overlay framebuffer is 960x540, upscaled by Tv to full screen). However, such functionality will probably require _a lot_ of effort to develop..

It may be easier to implement it as a widget.