It would pretty much require a small amount of custom development.
If you consider something like the thread preview tooltip, you could actually use that framework for this. Hovering over the element has to make an AJAX request to a specified URL which will then return a template which contains the contents you want to display inside the tooltip.
Our tooltip system is based on the title attribute, but the node descriptions use as separate element. No ajax involved. However, the JS is somewhat specific to that usage, mostly with respect to positioning.