Is there currently any way to display the current contents of registers, as with vim's :register command?
If yes, please consider obsolete.
If no, then it's not urgent. Just noting it down in the hope of pushing myself to implement it some day. (:
This is on the ToDo list, http://jvi.sourceforge.net/?TODO.html
(When I saw your message, I first thought that this must be implemented. After all, the :marks command is implemented...)
checked into Mercurial.