Can I get an entry by Matrix Block ID? For a url like domain.com/example/123 where 123 is a Matrix Block ID (not an Entry ID), can I get the associated entry for given block ID in a template?

Or, for a more general approach, what would be the best way to get that Matrix Block element and its Entry element when you only have a block ID?

Edit: so ideally:

{% set block = craft.matrixBlocks.id(craft.request.segment(2)).first() %}
{% set entry = block.getOwner() %}


...which isn't possible now.
At the time of this writing, the ideal solution isn't possible. But, as jpea suggested, creating a plugin was dead easy, so here it is:

Low Blocks

...which lets me use syntax like this:

{% set block = craft.lowBlocks.id(craft.request.segment(2)) %}
{% set entry = block.owner %}