Is there a way to know the node being viewed? I have a context where I'm placing a block onto a wiki page. Is there anyway for the block to know the node id of the wiki page? 

I'd like to write some code in the block's views-view--block--field.tpl.php template file to display something only to the wiki page's owner. With the block being placed on the wiki's page via context, the block needs what node(wiki) page it is displaying and who the node's owner is.
Wow - I just got a reply back from Acquia support that answers the issue. menu_get_object() seems to be one of those magically functions I never knew about. Neat.

global $user;
$node = menu_get_object();

if ($node &amp;&amp; $user) {

  print '&lt;br/&gt;node uid = ' . $node-&gt;uid;
  print '&lt;br/&gt;user uid = ' . $user-&gt;uid;

  if ($node-&gt;uid == $user-&gt;uid) {      
    print t('&lt;br/&gt;You are the author of the current node.');
  }

}