http://drupaleasy.com/blogs/ryanprice/2008/06/using-views-2-drupal-6-cre...
Dale asks a good question: before the release of Panels for Drupal 6, how can one associate a block with the node it's being displayed next to without writing a custom module? It turned out to be simpler than I expected. I actually started going down the path of custom modules, but in the process I noticed that Views still have the ability to load Arguments with PHP Code, and my solution wrote itself.
seems to add some of the extra fapi flexibility that we so often need