If it's a sidebar-type block, I'd recommend going the block plugin route; if you want the info to appear elsewhere, of course, it'd have to be a generic plugin. A couple of general notes:
. You should be able to download and install that plugin; create a custom block; and add your code to the block contents. I haven't used it myself yet, but give it a shot.
* Matt just wrote a block plugin howto: http://pkp.sfu.ca/wiki/index.php/Writing_a_Block_Plugin
. This should give you a much better idea on what block plugins do; how they work; and how to put your own together.
* Regardless of which way you go about implementing this, we'd love to see the results! Please let us know how it goes.